在Linux中，给kernel传递参数以控制其行为总共有三种方法：
1.build kernel之时的各个configuration选项。
2.当kernel启动之时，可以参数在kernel被GRUB或LILO等启动程序调用之时传递给kernel。
3.在kernel运行时，修改/proc或/sys目录下的文件。
这里我简单讲的就是第二种方式了，kernel在grub中配置的启动参数。
首先，kernel有哪些参数呢？ 在linux的源代码中，有这样的一个文档Documentation/kernel-parameters.txt，它介绍了kernel的各个参数及其意义。
其次，kernel启动参数以空格分隔，而且是严格区分大小写的（如：mem和MEM是不一样的）。
再次，对于module特有的kernel参数写法是这样的，[module name].[parameter=XX]，例如，igb.max_vfs=7这个kernel启动参数的效果就是相当于这样来动态加载module: modprobe igb max_vfs=7
另外，kernel是怎样处理这些启动参数的呢？ 启动参数通常是这样的形式： name[=value_1][,value_2]…[,value_10]
“name”是关键字，内核用它来识别应该把”关键字”后面的值传递给谁，也就是如何处理这个值，是传递给处理进程还是作为环境变量或者抛给”init”。值的个数限制为10，你可以通过再次使用该关键字使用超过10个的参数。 首先，kernel检查关键字是不是 ‘root=’, ‘nfsroot=’, ‘nfsaddrs=’, ‘ro’, ‘rw’, ‘debug’或’init’，然后内核在bootsetups数组里搜索于该关键字相关联的已注册的处理函数，如果找到相关的已注册的处理函数，则调用这些函数并把关键字后面的值作为参数传递给这些函数。比如，你在启动时设置参数name＝a,b,c,d，内核搜索bootsetups数组，如果发现”name”已注册，则调用”name”的设置函数如name_setup()，并把a,b,c,d传递给name_setup()执行。 所有型如”name＝value”参数，如果没有被上面所述的设置函数接收，将被解释为系统启动后的环境变量，比如”TERM=vt100″启动参数就会被作为一个启动后的环境变量。所有没有被内核设置函数接收也没又被设置成环境变量的参数都将留给init进程处理，比如”single”。
下面简单总结一下我在工作中常用到的一些kernel启动参数吧。
根磁盘相关启动参数：
root #指出启动的根文件系统 如：root=/dev/sda1
ro #指定根设备在启动过程中为read-only，默认情况下一般都是这样配的
rw #和ro类似，它是规定为read-write，可写
rootfstype #根文件系统类型，如：rootfstype=ext4
Console和kernel log相关启动参数：
console #console的设备和选项，如：console=tty0 console=ttyS0
debug #enable kernel debugging 启动中的所有debug信息都会打印到console上
quiet #disable all log messages 将kernel log level设置为KERN_WARNING，在启动中只非常严重的信息
loglevel #设置默认的console日志级别，如：loglevel=7 （0~7的数字分别为：KERN_EMERG,..,KERN_DEBUG）
time #设置在每条kernel log信息前加一个时间戳
内存相关的启动参数：
mem #指定kernel使用的内存量，mem=n[KMG]
hugepages #设置大页表页（4MB大小）的最多个数，hugepages=n
CPU相关的启动参数：
mce # Enable the machine check exception feature.
nosmp #Run as a single-processor machine. 不使用SMP（多处理器）
max_cpus #max_cpus=n, SMP系统最多能使用的CPU个数（即使系统中有大于n个的CPU）
Ramdisk相关的启动参数：
initrd #指定初始化ramdisk的位置，initrd=filename
noinitrd #不使用initrd的配置，即使配置了initrd参数
初始化相关启动参数：
init #在启动时去执行的程序，init=filename，默认值为/sbin/init
PCI相关的启动参数：
pci #pci相关的选项，我常使用pci=assign_buses，也使用过pci=nomsi
SELinux相关启动参数：
enforcing #SELinux enforcing状态的开关，enforcing=0表示仅仅是记录危险而不是阻止访问，enforcing=1完全enable，默认值是0
selinux #在启动时关闭或开启SELinux，selinux=0表示关闭，selinux=1表示开启selinux
另外，还是用max_loop来指定最多可使用的回路设备。
在Redhat的系统中，还有个经常看到的kernel启动参数——rhgb，rhgb表示redhat graphics boot，就是会看到图片来代替启动过程中显示的文本信息，这些信息在启动后用dmesg也可以看到
rhgb = redhat graphical boot – This is a GUI mode booting screen with most of the information hidden while the user sees a rotating activity icon spining and brief information as to what the computer is doing.
quiet = hides the majority of boot messages before rhgb starts. These are supposed to make the common user more comfortable. They get alarmed about seeing the kernel and initializing messages, so they hide them for their comfort.
参考资料:
linux kernel documents
《Linux kernel in a nutshell》
---------------------转载内容结束------------------------------------------
转载自：http://smilejay.com/2011/10/kernel_parameters/
顺便贴一个内核版本为2.6.32.1的内核的kernel-parameters文档
Kernel Parameters
~~~~~~~~~~~~~~~~~
The following is a consolidated list of the kernel parameters as implemented
(mostly) by the __setup() macro and sorted into English Dictionary order
(defined as ignoring all punctuation and sorting digits before letters in a
case insensitive manner), and with descriptions where known.
Module parameters for loadable modules are specified only as the
parameter name with optional '=' and value as appropriate, such as:
modprobe usbcore blinkenlights=1
Module parameters for modules that are built into the kernel image
are specified on the kernel command line with the module name plus
'.' plus parameter name, with '=' and value if appropriate, such as:
usbcore.blinkenlights=1
Hyphens (dashes) and underscores are equivalent in parameter names, so
log_buf_len=1M print-fatal-signals=1
can also be entered as
log-buf-len=1M print_fatal_signals=1
This document may not be entirely up to date and comprehensive. The command
"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
module. Loadable modules, after being loaded into the running kernel, also
reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
parameters may be changed at runtime by the command
"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
The parameters listed below are only valid if certain kernel build options were
enabled and if respective hardware is present. The text in square brackets at
the beginning of each description states the restrictions within which a
parameter is applicable:
ACPI ACPI support is enabled.
AGP AGP (Accelerated Graphics Port) is enabled.
ALSA ALSA sound support is enabled.
APIC APIC support is enabled.
APM Advanced Power Management support is enabled.
AVR32 AVR32 architecture is enabled.
AX25 Appropriate AX.25 support is enabled.
BLACKFIN Blackfin architecture is enabled.
DRM Direct Rendering Management support is enabled.
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
EFI EFI Partitioning (GPT) is enabled
EIDE EIDE/ATAPI support is enabled.
FB The frame buffer device is enabled.
GCOV GCOV profiling is enabled.
HW Appropriate hardware is enabled.
IA-64 IA-64 architecture is enabled.
IMA Integrity measurement architecture is enabled.
IOSCHED More than one I/O scheduler is enabled.
IP_PNP IP DHCP, BOOTP, or RARP is enabled.
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
JOY Appropriate joystick support is enabled.
KVM Kernel Virtual Machine support is enabled.
LIBATA Libata driver is enabled
LP Printer support is enabled.
LOOP Loopback device support is enabled.
M68k M68k architecture is enabled.
These options have more detailed description inside of
Documentation/m68k/kernel-options.txt.
MCA MCA bus support is enabled.
MDA MDA console support is enabled.
MOUSE Appropriate mouse support is enabled.
MSI Message Signaled Interrupts (PCI).
MTD MTD (Memory Technology Device) support is enabled.
NET Appropriate network support is enabled.
NUMA NUMA support is enabled.
GENERIC_TIME The generic timeofday code is enabled.
NFS Appropriate NFS support is enabled.
OSS OSS sound support is enabled.
PV_OPS A paravirtualized kernel is enabled.
PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
PARISC The PA-RISC architecture is enabled.
PCI PCI bus support is enabled.
PCIE PCI Express support is enabled.
PCMCIA The PCMCIA subsystem is enabled.
PNP Plug & Play support is enabled.
PPC PowerPC architecture is enabled.
PPT Parallel port support is enabled.
PS2 Appropriate PS/2 support is enabled.
RAM RAM disk support is enabled.
ROOTPLUG The example Root Plug LSM is enabled.
S390 S390 architecture is enabled.
SCSI Appropriate SCSI support is enabled.
A lot of drivers has their options described inside of
Documentation/scsi/.
SECURITY Different security models are enabled.
SELINUX SELinux support is enabled.
SERIAL Serial support is enabled.
SH SuperH architecture is enabled.
SMP The kernel is an SMP kernel.
SPARC Sparc architecture is enabled.
SWSUSP Software suspend (hibernation) is enabled.
SUSPEND System suspend states are enabled.
FTRACE Function tracing enabled.
TS Appropriate touchscreen support is enabled.
UMS USB Mass Storage support is enabled.
USB USB support is enabled.
USBHID USB Human Interface Device support is enabled.
V4L Video For Linux support is enabled.
VGA The VGA console has been enabled.
VT Virtual terminal support is enabled.
WDT Watchdog support is enabled.
XT IBM PC/XT MFM hard disk support is enabled.
X86-32 X86-32, aka i386 architecture is enabled.
X86-64 X86-64 architecture is enabled.
More X86-64 boot options can be found in
Documentation/x86/x86_64/boot-options.txt .
X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
In addition, the following text indicates that the option:
BUGS= Relates to possible processor bugs on the said processor.
KNL Is a kernel start-up parameter.
BOOT Is a boot loader parameter.
Parameters denoted with BOOT are actually interpreted by the boot
loader, and have no meaning to the kernel directly.
Do not modify the syntax of boot loader parameters without extreme
need or coordination with <Documentation/x86/boot.txt>.
There are also arch-specific kernel-parameters not documented here.
See for example <Documentation/x86/x86_64/boot-options.txt>.
Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
a trailing = on the name of any parameter states that that parameter will
be entered as an environment variable, whereas its absence indicates that
it will appear as a kernel argument readable via /proc/cmdline by programs
running once the system is up.
The number of kernel parameters is not limited, but the length of the
complete command line (parameters including spaces etc.) is limited to
a fixed number of characters. This limit depends on the architecture
and is between 256 and 4096 characters. It is defined in the file
./include/asm/setup.h as COMMAND_LINE_SIZE.
acpi= [HW,ACPI,X86]
Advanced Configuration and Power Interface
Format: { force | off | ht | strict | noirq | rsdt }
force -- enable ACPI if default was off
off -- disable ACPI if default was on
noirq -- do not use ACPI for IRQ routing
ht -- run only enough ACPI to enable Hyper Threading
strict -- Be less tolerant of platforms that are not
strictly ACPI specification compliant.
rsdt -- prefer RSDT over (default) XSDT
See also Documentation/power/pm.txt, pci=noacpi
acpi_apic_instance= [ACPI, IOAPIC]
Format: <int>
2: use 2nd APIC table, if available
1,0: use 1st APIC table
default: 0
acpi_backlight= [HW,ACPI]
acpi_backlight=vendor
acpi_backlight=video
If set to vendor, prefer vendor specific driver
(e.g. thinkpad_acpi, sony_acpi, etc.) instead
of the ACPI video.ko driver.
acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Format: <int>
CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
debug output. Bits in debug_layer correspond to a
_COMPONENT in an ACPI source file, e.g.,
#define _COMPONENT ACPI_PCI_COMPONENT
Bits in debug_level correspond to a level in
ACPI_DEBUG_PRINT statements, e.g.,
ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
The debug_level mask defaults to "info". See
Documentation/acpi/debug.txt for more information about
debug layers and levels.
Enable processor driver info messages:
acpi.debug_layer=0x20000000
Enable PCI/PCI interrupt routing info messages:
acpi.debug_layer=0x400000
Enable AML "Debug" output, i.e., stores to the Debug
object while interpreting AML:
acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Enable all messages related to ACPI hardware:
acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Some values produce so much output that the system is
unusable. The "log_buf_len" parameter may be useful
if you need to capture more output.
acpi_display_output= [HW,ACPI]
acpi_display_output=vendor
acpi_display_output=video
See above.
acpi_irq_balance [HW,ACPI]
ACPI will balance active IRQs
default in APIC mode
acpi_irq_nobalance [HW,ACPI]
ACPI will not move active IRQs (default)
default in PIC mode
acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Format: <irq>,<irq>...
acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
use by PCI
Format: <irq>,<irq>...
acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
Format: To spoof as Windows 98: ="Microsoft Windows"
acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
acpi_osi="string1" # add string1 -- only one string
acpi_osi="!string2" # remove built-in string2
acpi_osi= # disable all strings
acpi_pm_good [X86]
Override the pmtimer bug detection: force the kernel
to assume that this machine's pmtimer latches its value
and always returns good values.
acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Format: { level | edge | high | low }
acpi_serialize [HW,ACPI] force serialization of AML methods
acpi_skip_timer_override [HW,ACPI]
Recognize and ignore IRQ0/pin2 Interrupt Override.
For broken nForce2 BIOS resulting in XT-PIC timer.
acpi_sleep= [HW,ACPI] Sleep options
Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
old_ordering, s4_nonvs }
See Documentation/power/video.txt for information on
s3_bios and s3_mode.
s3_beep is for debugging; it makes the PC's speaker beep
as soon as the kernel's real-mode entry point is called.
s4_nohwsig prevents ACPI hardware signature from being
used during resume from hibernation.
old_ordering causes the ACPI 1.0 ordering of the _PTS
control method, with respect to putting devices into
low power states, to be enforced (the ACPI 2.0 ordering
of _PTS is used by default).
s4_nonvs prevents the kernel from saving/restoring the
ACPI NVS memory during hibernation.
acpi_use_timer_override [HW,ACPI]
Use timer override. For some broken Nvidia NF5 boards
that require a timer override, but don't have HPET
acpi_enforce_resources= [ACPI]
{ strict | lax | no }
Check for resource conflicts between native drivers
and ACPI OperationRegions (SystemIO and SystemMemory
only). IO ports and memory declared in ACPI might be
used by the ACPI subsystem in arbitrary AML code and
can interfere with legacy drivers.
strict (default): access to resources claimed by ACPI
is denied; legacy drivers trying to access reserved
resources will fail to bind to device using them.
lax: access to resources claimed by ACPI is allowed;
legacy drivers trying to access reserved resources
will bind successfully but a warning message is logged.
no: ACPI OperationRegions are not marked as reserved,
no further checks are performed.
ad1848= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<type>
add_efi_memmap [EFI; X86] Include EFI memory map in
kernel's map of available physical RAM.
advansys= [HW,SCSI]
See header of drivers/scsi/advansys.c.
advwdt= [HW,WDT] Advantech WDT
Format: <iostart>,<iostop>
aedsp16= [HW,OSS] Audio Excel DSP 16
Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
See also header of sound/oss/aedsp16.c.
agp= [AGP]
{ off | try_unsupported }
off: disable AGP support
try_unsupported: try to drive unsupported chipsets
(may crash computer or cause data corruption)
aha152x= [HW,SCSI]
See Documentation/scsi/aha152x.txt.
aha1542= [HW,SCSI]
Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
aic7xxx= [HW,SCSI]
See Documentation/scsi/aic7xxx.txt.
aic79xx= [HW,SCSI]
See Documentation/scsi/aic79xx.txt.
amd_iommu= [HW,X86-84]
Pass parameters to the AMD IOMMU driver in the system.
Possible values are:
isolate - enable device isolation (each device, as far
as possible, will get its own protection
domain) [default]
share - put every device behind one IOMMU into the
same protection domain
fullflush - enable flushing of IO/TLB entries when
they are unmapped. Otherwise they are
flushed before they will be reused, which
is a lot of faster
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Format: <a>,<b>
See also Documentation/kernel/input/joystick.txt
analog.map= [HW,JOY] Analog joystick and gamepad support
Specifies type or capabilities of an analog joystick
connected to one of 16 gameports
Format: <type1>,<type2>,..<type16>
apc= [HW,SPARC]
Power management functions (SPARCstation-4/5 + deriv.)
Format: noidle
Disable APC CPU standby support. SPARCstation-Fox does
not play well with APC CPU idle - disable it if you have
APC and your system crashes randomly.
apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Change the output verbosity whilst booting
Format: { quiet (default) | verbose | debug }
Change the amount of debugging information output
when initialising the APIC and IO-APIC components.
apm= [APM] Advanced Power Management
See header of arch/x86/kernel/apm_32.c.
arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
Format: <io>,<irq>,<nodeID>
ataflop= [HW,M68k]
atarimouse= [HW,MOUSE] Atari Mouse
atascsi= [HW,SCSI] Atari SCSI
atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
EzKey and similar keyboards
atkbd.reset= [HW] Reset keyboard during initialization
atkbd.set= [HW] Select keyboard code set
Format: <int> (2 = AT (default), 3 = PS/2)
atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
keyboards
atkbd.softraw= [HW] Choose between synthetic and real raw mode
Format: <bool> (0 = real, 1 = synthetic (default))
atkbd.softrepeat= [HW]
Use software keyboard repeat
autotest [IA64]
baycom_epp= [HW,AX25]
Format: <io>,<mode>
baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
Format: <io>,<mode>
See header of drivers/net/hamradio/baycom_par.c.
baycom_ser_fdx= [HW,AX25]
BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Format: <io>,<irq>,<mode>[,<baud>]
See header of drivers/net/hamradio/baycom_ser_fdx.c.
baycom_ser_hdx= [HW,AX25]
BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Format: <io>,<irq>,<mode>
See header of drivers/net/hamradio/baycom_ser_hdx.c.
boot_delay= Milliseconds to delay each printk during boot.
Values larger than 10 seconds (10000) are changed to
no delay (0).
Format: integer
bootmem_debug [KNL] Enable bootmem allocator debug messages.
bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
bttv.radio= Most important insmod options are available as
kernel args too.
bttv.pll= See Documentation/video4linux/bttv/Insmod-options
bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
BusLogic= [HW,SCSI]
See drivers/scsi/BusLogic.c, comment before function
BusLogic_ParseDriverOptions().
c101= [NET] Moxa C101 synchronous serial card
cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Sometimes CPU hardware bugs make them report the cache
size incorrectly. The kernel will attempt work arounds
to fix known problems, but for some CPUs it is not
possible to determine what the correct size should be.
This option provides an override for these situations.
capability.disable=
[SECURITY] Disable capabilities. This would normally
be used only if an alternative security model is to be
configured. Potentially dangerous and should only be
used if you are entirely sure of the consequences.
ccw_timeout_log [S390]
See Documentation/s390/CommonIO for details.
cgroup_disable= [KNL] Disable a particular controller
Format: {name of the controller(s) to disable}
{Currently supported controllers - "memory"}
checkreqprot [SELINUX] Set initial checkreqprot flag value.
Format: { "0" | "1" }
See security/selinux/Kconfig help text.
0 -- check protection applied by kernel (includes
any implied execute protection).
1 -- check protection requested by application.
Default value is set via a kernel config option.
Value can be changed at runtime via
/selinux/checkreqprot.
cio_ignore= [S390]
See Documentation/s390/CommonIO for details.
clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
[Deprecated]
Forces specified clocksource (if available) to be used
when calculating gettimeofday(). If specified
clocksource is not available, it defaults to PIT.
Format: { pit | tsc | cyclone | pmtmr }
clocksource= [GENERIC_TIME] Override the default clocksource
Format: <string>
Override the default clocksource and use the clocksource
with the name specified.
Some clocksource names to choose from, depending on
the platform:
[all] jiffies (this is the base, fallback clocksource)
[ACPI] acpi_pm
[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
pxa_timer,timer3,32k_counter,timer0_1
[AVR32] avr32
[X86-32] pit,hpet,tsc,vmi-timer;
scx200_hrt on Geode; cyclone on IBM x440
[MIPS] MIPS
[PARISC] cr16
[S390] tod
[SH] SuperH
[SPARC64] tick
[X86-64] hpet,tsc
clearcpuid=BITNUM [X86]
Disable CPUID feature X for the kernel. See
arch/x86/include/asm/cpufeature.h for the valid bit
numbers. Note the Linux specific bits are not necessarily
stable over kernel options, but the vendor specific
ones should be.
Also note that user programs calling CPUID directly
or using the feature without checking anything
will still see it. This just prevents it from
being used by the kernel or shown in /proc/cpuinfo.
Also note the kernel might malfunction if you disable
some critical bits.
cmo_free_hint= [PPC] Format: { yes | no }
Specify whether pages are marked as being inactive
when they are freed. This is used in CMO environments
to determine OS memory pressure for page stealing by
a hypervisor.
Default: yes
code_bytes [X86] How many bytes of object code to print
in an oops report.
Range: 0 - 8192
Default: 64
com20020= [HW,NET] ARCnet - COM20020 chipset
Format:
<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
Format: <io>[,<irq>]
com90xx= [HW,NET]
ARCnet - COM90xx chipset (memory-mapped buffers)
Format: <io>[,<irq>[,<memstart>]]
condev= [HW,S390] console device
conmode=
console= [KNL] Output console device and options.
tty<n> Use the virtual console device <n>.
ttyS<n>[,options]
ttyUSB0[,options]
Use the specified serial port. The options are of
the form "bbbbpnf", where "bbbb" is the baud rate,
"p" is parity ("n", "o", or "e"), "n" is number of
bits, and "f" is flow control ("r" for RTS or
omit it). Default is "9600n8".
See Documentation/serial-console.txt for more
information. See
Documentation/networking/netconsole.txt for an
alternative.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address,
switching to the matching ttyS device later. The
options are the same as for ttyS, above.
If the device connected to the port is not a TTY but a braille
device, prepend "brl," before the device type, for instance
console=brl,ttyS0
For now, only VisioBraille is supported.
consoleblank= [KNL] The console blank (screen saver) timeout in
seconds. Defaults to 10*60 = 10mins. A value of 0
disables the blank timer.
coredump_filter=
[KNL] Change the default value for
/proc/<pid>/coredump_filter.
See also Documentation/filesystems/proc.txt.
cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Format:
<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
crashkernel=nn[KMG]@ss[KMG]
[KNL] Reserve a chunk of physical memory to
hold a kernel to switch to with kexec on panic.
crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory
in the running system. The syntax of range is
start-[end] where start and end are both
a memory unit (amount[KMG]). See also
Documentation/kdump/kdump.txt for a example.
cs89x0_dma= [HW,NET]
Format: <dma>
cs89x0_media= [HW,NET]
Format: { rj45 | aui | bnc }
dasd= [HW,NET]
See header of drivers/s390/block/dasd_devmap.c.
db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
(one device per port)
Format: <port#>,<type>
See also Documentation/input/joystick-parport.txt
debug [KNL] Enable kernel debugging (events log level).
debug_locks_verbose=
[KNL] verbose self-tests
Format=<0|1>
Print debugging info while doing the locking API
self-tests.
We default to 0 (no extra messages), setting it to
1 will print _a lot_ more information - normally
only useful to kernel developers.
debug_objects [KNL] Enable object debugging
no_debug_objects
[KNL] Disable object debugging
debugpat [X86] Enable PAT debugging
decnet.addr= [HW,NET]
Format: <area>[,<node>]
See also Documentation/networking/decnet.txt.
default_hugepagesz=
[same as hugepagesz=] The size of the default
HugeTLB page size. This is the size represented by
the legacy /proc/ hugepages APIs, used for SHM, and
default size when mounting hugetlbfs filesystems.
Defaults to the default architecture's huge page size
if not specified.
dhash_entries= [KNL]
Set number of hash buckets for dentry cache.
digi= [HW,SERIAL]
IO parameters + enable/disable command.
digiepca= [HW,SERIAL]
See drivers/char/README.epca and
Documentation/serial/digiepca.txt.
disable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous
to discrete, to make X server driver able to add WB
entry later. This parameter disables that.
disable_mtrr_trim [X86, Intel and AMD only]
By default the kernel will trim any uncacheable
memory out of your available memory pool based on
MTRR settings. This parameter disables that behavior,
possibly causing your machine to run very slowly.
disable_timer_pin_1 [X86]
Disable PIN 1 of APIC timer
Can be useful to work around chipset bugs.
dmasound= [HW,OSS] Sound subsystem buffers
dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
this option disables the debugging code at boot.
dma_debug_entries=<number>
This option allows to tune the number of preallocated
entries for DMA-API debugging code. One entry is
required per DMA-API allocation. Use this if the
DMA-API debugging code disables itself because the
architectural default is too low.
dma_debug_driver=<driver_name>
With this option the DMA-API debugging driver
filter feature can be enabled at boot time. Just
pass the driver to filter for as the parameter.
The filter can be disabled or changed to another
driver later using sysfs.
dscc4.setup= [NET]
dtc3181e= [HW,SCSI]
dynamic_printk Enables pr_debug()/dev_dbg() calls if
CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
These can also be switched on/off via
<debugfs>/dynamic_printk/modules
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address.
The options are the same as for ttyS, above.
earlyprintk= [X86,SH,BLACKFIN]
earlyprintk=vga
earlyprintk=serial[,ttySn[,baudrate]]
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
Append ",keep" to not disable it when the real console
takes over.
Only vga or serial or usb debug port at a time.
Currently only ttyS0 and ttyS1 are supported.
Interaction with the standard serial driver is not
very good.
The VGA output is eventually overwritten by the real
console.
eata= [HW,SCSI]
edd= [EDD]
Format: {"off" | "on" | "skip[mbr]"}
eisa_irq_edge= [PARISC,HW]
See header of drivers/parisc/eisa.c.
elanfreq= [X86-32]
See comment before function elanfreq_setup() in
arch/x86/kernel/cpu/cpufreq/elanfreq.c.
elevator= [IOSCHED]
Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
See Documentation/block/as-iosched.txt and
Documentation/block/deadline-iosched.txt for details.
elfcorehdr= [IA64,PPC,SH,X86]
Specifies physical address of start of kernel core
image elf header. Generally kexec loader will
pass this option to capture kernel.
See Documentation/kdump/kdump.txt for details.
enable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous
to discrete, to make X server driver able to add WB
entry later. This parameter enables that.
enable_timer_pin_1 [X86]
Enable PIN 1 of APIC timer
Can be useful to work around chipset bugs
(in particular on some ATI chipsets).
The kernel tries to set a reasonable default.
enforcing [SELINUX] Set initial enforcing status.
Format: {"0" | "1"}
See security/selinux/Kconfig help text.
0 -- permissive (log only, no denials).
1 -- enforcing (deny and log).
Default value is 0.
Value can be changed at runtime via /selinux/enforce.
ether= [HW,NET] Ethernet cards parameters
This option is obsoleted by the "netdev=" option, which
has equivalent usage. See its documentation for details.
eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
Format: <io>[,<irq>]
failslab=
fail_page_alloc=
fail_make_request=[KNL]
General fault injection mechanism.
Format: <interval>,<probability>,<space>,<times>
See also /Documentation/fault-injection/.
fd_mcs= [HW,SCSI]
See header of drivers/scsi/fd_mcs.c.
fdomain= [HW,SCSI]
See header of drivers/scsi/fdomain.c.
floppy= [HW]
See Documentation/blockdev/floppy.txt.
force_pal_cache_flush
[IA-64] Avoid check_sal_cache_flush which may hang on
buggy SAL_CACHE_FLUSH implementations. Using this
parameter will force ia64_sal_cache_flush to call
ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
ftrace=[tracer]
[FTRACE] will set and start the specified tracer
as early as possible in order to facilitate early
boot debugging.
ftrace_dump_on_oops
[FTRACE] will dump the trace buffers on oops.
ftrace_filter=[function-list]
[FTRACE] Limit the functions traced by the function
tracer at boot up. function-list is a comma separated
list of functions. This list can be changed at run
time by the set_ftrace_filter file in the debugfs
tracing directory.
ftrace_notrace=[function-list]
[FTRACE] Do not trace the functions specified in
function-list. This list can be changed at run time
by the set_ftrace_notrace file in the debugfs
tracing directory.
gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
support via parallel port (up to 5 devices per port)
Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
See also Documentation/input/joystick-parport.txt
gamma= [HW,DRM]
gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
Format: off | on
default: on
gcov_persist= [GCOV] When non-zero (default), profiling data for
kernel modules is saved and remains accessible via
debugfs, even when the module is unloaded/reloaded.
When zero, profiling data is discarded and associated
debugfs files are removed at module unload time.
gdth= [HW,SCSI]
See header of drivers/scsi/gdth.c.
gpt [EFI] Forces disk with valid GPT signature but
invalid Protective MBR to be treated as GPT.
gvp11= [HW,SCSI]
hashdist= [KNL,NUMA] Large hashes allocated during boot
are distributed across NUMA nodes. Defaults on
for 64bit NUMA, off otherwise.
Format: 0 | 1 (for off | on)
hcl= [IA-64] SGI's Hardware Graph compatibility layer
hd= [EIDE] (E)IDE hard drive subsystem geometry
Format: <cyl>,<head>,<sect>
highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
size of <nn>. This works even on boxes that have no
highmem otherwise. This also works to reduce highmem
size on bigger boxes.
highres= [KNL] Enable/disable high resolution timer mode.
Valid parameters: "on", "off"
Default: "on"
hisax= [HW,ISDN]
See Documentation/isdn/README.HiSax.
hlt [BUGS=ARM,SH]
hpet= [X86-32,HPET] option to control HPET usage
Format: { enable (default) | disable | force |
verbose }
disable: disable HPET and use PIT instead
force: allow force enabled of undocumented chips (ICH4,
VIA, nVidia)
verbose: show contents of HPET registers during setup
hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
On x86-64 and powerpc, this option can be specified
multiple times interleaved with hugepages= to reserve
huge pages of different sizes. Valid pages sizes on
x86-64 are 2M (when the CPU supports "pse") and 1G
(when the CPU supports the "pdpe1gb" cpuinfo flag)
Note that 1GB pages can only be allocated at boot time
using hugepages= and not freed afterwards.
hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
terminal devices. Valid values: 0..8
hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
If specified, z/VM IUCV HVC accepts connections
from listed z/VM user IDs only.
i2c_bus= [HW] Override the default board specific I2C bus speed
or register an additional I2C bus that is not
registered from board initialization code.
Format:
<bus_id>,<clkrate>
i8042.debug [HW] Toggle i8042 debug mode
i8042.direct [HW] Put keyboard port into non-translated mode
i8042.dumbkbd [HW] Pretend that controller can only read data from
keyboard and cannot control its state
(Don't attempt to blink the leds)
i8042.noaux [HW] Don't check for auxiliary (== mouse) port
i8042.nokbd [HW] Don't check/create keyboard port
i8042.noloop [HW] Disable the AUX Loopback command while probing
for the AUX port
i8042.nomux [HW] Don't check presence of an active multiplexing
controller
i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
controllers
i8042.panicblink=
[HW] Frequency with which keyboard LEDs should blink
when kernel panics (default is 0.5 sec)
i8042.reset [HW] Reset the controller during init and cleanup
i8042.unlock [HW] Unlock (ignore) the keylock
i810= [HW,DRM]
i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
indicates that the driver is running on unsupported
hardware.
i8k.force [HW] Activate i8k driver even if SMM BIOS signature
does not match list of supported models.
i8k.power_status
[HW] Report power status in /proc/i8k
(disabled by default)
i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
capability is set.
ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
See Documentation/mca.txt.
icn= [HW,ISDN]
Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
ide-core.nodma= [HW] (E)IDE subsystem
Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
.cdrom .chs .ignore_cable are additional options
See Documentation/ide/ide.txt.
ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
Claim all unknown PCI IDE storage controllers.
idle= [X86]
Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
Poll forces a polling idle loop that can slightly
improve the performance of waking up a idle CPU, but
will use a lot of power and make the system run hot.
Not recommended.
idle=mwait: On systems which support MONITOR/MWAIT but
the kernel chose to not use it because it doesn't save
as much power as a normal idle loop, use the
MONITOR/MWAIT idle loop anyways. Performance should be
the same as idle=poll.
idle=halt: Halt is forced to be used for CPU idle.
In such case C2/C3 won't be used again.
idle=nomwait: Disable mwait for CPU C-states
ignore_loglevel [KNL]
Ignore loglevel setting - this will print /all/
kernel messages to the console. Useful for debugging.
ihash_entries= [KNL]
Set number of hash buckets for inode cache.
ima_audit= [IMA]
Format: { "0" | "1" }
0 -- integrity auditing messages. (Default)
1 -- enable informational integrity auditing messages.
ima_hash= [IMA]
Format: { "sha1" | "md5" }
default: "sha1"
ima_tcb [IMA]
Load a policy which meets the needs of the Trusted
Computing Base. This means IMA will measure all
programs exec'd, files mmap'd for exec, and all files
opened for read by uid=0.
in2000= [HW,SCSI]
See header of drivers/scsi/in2000.c.
init= [KNL]
Format: <full_path>
Run specified binary instead of /sbin/init as init
process.
initcall_debug [KNL] Trace initcalls as they are executed. Useful
for working out where the kernel is dying during
startup.
initrd= [BOOT] Specify the location of the initial ramdisk
inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
Format: <irq>
intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
on
Enable intel iommu driver.
off
Disable intel iommu driver.
igfx_off [Default Off]
By default, gfx is mapped as normal device. If a gfx
device has a dedicated DMAR unit, the DMAR unit is
bypassed by not enabling DMAR with this option. In
this case, gfx device will use physical address for
DMA.
forcedac [x86_64]
With this option iommu will not optimize to look
for io virtual address below 32 bit forcing dual
address cycle on pci bus for cards supporting greater
than 32 bit addressing. The default is to look
for translation below 32 bit and if not available
then look in the higher range.
strict [Default Off]
With this option on every unmap_single operation will
result in a hardware IOTLB flush operation as opposed
to batching them for performance.
inttest= [IA64]
iomem= Disable strict checking of access to MMIO memory
strict regions from userspace.
relaxed
iommu= [x86]
off
force
noforce
biomerge
panic
nopanic
merge
nomerge
forcesac
soft
pt [x86, IA64]
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
io_delay= [X86] I/O delay method
0x80
Standard port 0x80 based delay
0xed
Alternate port 0xed based delay (needed on some systems)
udelay
Simple two microseconds delay
none
No delay
ip= [IP_PNP]
See Documentation/filesystems/nfsroot.txt.
ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
See comment before ip2_setup() in
drivers/char/ip2/ip2base.c.
ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
See header of drivers/scsi/ips.c.
irqfixup [HW]
When an interrupt is not handled search all handlers
for it. Intended to get systems with badly broken
firmware running.
irqpoll [HW]
When an interrupt is not handled search all handlers
for it. Also check all handlers each timer
interrupt. Intended to get systems with badly broken
firmware running.
isapnp= [ISAPNP]
Format: <RDP>,<reset>,<pci_scan>,<verbosity>
isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Format:
<cpu number>,...,<cpu number>
or
<cpu number>-<cpu number>
(must be a positive range in ascending order)
or a mixture
<cpu number>,...,<cpu number>-<cpu number>
This option can be used to specify one or more CPUs
to isolate from the general SMP balancing and scheduling
algorithms. You can move a process onto or off an
"isolated" CPU via the CPU affinity syscalls or cpuset.
<cpu number> begins at 0 and the maximum value is
"number of CPUs in system - 1".
This option is the preferred way to isolate CPUs. The
alternative -- manually setting the CPU mask of all
tasks in the system -- can cause problems and
suboptimal load balancer performance.
iucv= [HW,NET]
js= [HW,JOY] Analog joystick
See Documentation/input/joystick.txt.
keepinitrd [HW,ARM]
kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
specifies the amount of memory usable by the kernel
for non-movable allocations. The requested amount is
spread evenly throughout all nodes in the system. The
remaining memory in each node is used for Movable
pages. In the event, a node is too small to have both
kernelcore and Movable pages, kernelcore pages will
take priority and other nodes will have a larger number
of kernelcore pages. The Movable zone is used for the
allocation of pages that may be reclaimed or moved
by the page migration subsystem. This means that
HugeTLB pages may not be allocated from this zone.
Note that allocations like PTEs-from-HighMem still
use the HighMem zone if it exists, and the Normal
zone if it does not.
kgdboc= [HW] kgdb over consoles.
Requires a tty driver that supports console polling.
(only serial supported for now)
Format: <serial_device>[,baud]
kmac= [MIPS] korina ethernet MAC address.
Configure the RouterBoard 532 series on-chip
Ethernet adapter MAC address.
kmemleak= [KNL] Boot-time kmemleak enable/disable
Valid arguments: on, off
Default: on
kstack=N [X86] Print N words from the kernel stack
in oops dumps.
kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
Default is 0 (don't ignore, but inject #GP)
kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
Default is 1 (enabled)
kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Default is 0 (off)
kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
for all guests.
Default is 1 (enabled) if in 64bit or 32bit-PAE mode
kvm-intel.bypass_guest_pf=
[KVM,Intel] Disables bypassing of guest page faults
on Intel chips. Default is 1 (enabled)
kvm-intel.ept= [KVM,Intel] Disable extended page tables
(virtualized MMU) support on capable Intel chips.
Default is 1 (enabled)
kvm-intel.emulate_invalid_guest_state=
[KVM,Intel] Enable emulation of invalid guest states
Default is 0 (disabled)
kvm-intel.flexpriority=
[KVM,Intel] Disable FlexPriority feature (TPR shadow).
Default is 1 (enabled)
kvm-intel.unrestricted_guest=
[KVM,Intel] Disable unrestricted guest feature
(virtualized real and unpaged mode) on capable
Intel chips. Default is 1 (enabled)
kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
feature (tagged TLBs) on capable Intel chips.
Default is 1 (enabled)
l2cr= [PPC]
l3cr= [PPC]
lapic [X86-32,APIC] Enable the local APIC even if BIOS
disabled it.
lapic_timer_c2_ok [X86,APIC] trust the local apic timer
in C2 power state.
libata.dma= [LIBATA] DMA control
libata.dma=0 Disable all PATA and SATA DMA
libata.dma=1 PATA and SATA Disk DMA only
libata.dma=2 ATAPI (CDROM) DMA only
libata.dma=4 Compact Flash DMA only
Combinations also work, so libata.dma=3 enables DMA
for disks and CDROMs, but not CFs.
libata.ignore_hpa= [LIBATA] Ignore HPA limit
libata.ignore_hpa=0 keep BIOS limits (default)
libata.ignore_hpa=1 ignore limits, using full disk
libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
when set.
Format: <int>
libata.force= [LIBATA] Force configurations. The format is comma
separated list of "[ID:]VAL" where ID is
PORT[:DEVICE]. PORT and DEVICE are decimal numbers
matching port, link or device. Basically, it matches
the ATA ID string printed on console by libata. If
the whole ID part is omitted, the last PORT and DEVICE
values are used. If ID hasn't been specified yet, the
configuration applies to all ports, links and devices.
If only DEVICE is omitted, the parameter applies to
the port and all links and devices behind it. DEVICE
number of 0 either selects the first device or the
first fan-out link behind PMP device. It does not
select the host link. DEVICE number of 15 selects the
host link and device attached to it.
The VAL specifies the configuration to force. As long
as there's no ambiguity shortcut notation is allowed.
For example, both 1.5 and 1.5G would work for 1.5Gbps.
The following configurations can be forced.
* Cable type: 40c, 80c, short40c, unk, ign or sata.
Any ID with matching PORT is used.
* SATA link speed limit: 1.5Gbps or 3.0Gbps.
* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
udma[/][16,25,33,44,66,100,133] notation is also
allowed.
* [no]ncq: Turn on or off NCQ.
* nohrst, nosrst, norst: suppress hard, soft
and both resets.
If there are multiple matching configurations changing
the same attribute, the last one is used.
lmb=debug [KNL] Enable lmb debug messages.
load_ramdisk= [RAM] List of ramdisks to load from floppy
See Documentation/blockdev/ramdisk.txt.
lockd.nlm_grace_period=P [NFS] Assign grace period.
Format: <integer>
lockd.nlm_tcpport=N [NFS] Assign TCP port.
Format: <integer>
lockd.nlm_timeout=T [NFS] Assign timeout value.
Format: <integer>
lockd.nlm_udpport=M [NFS] Assign UDP port.
Format: <integer>
logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
Format: <irq>
loglevel= All Kernel Messages with a loglevel smaller than the
console loglevel will be printed to the console. It can
also be changed with klogd or other programs. The
loglevels are defined as follows:
0 (KERN_EMERG) system is unusable
1 (KERN_ALERT) action must be taken immediately
2 (KERN_CRIT) critical conditions
3 (KERN_ERR) error conditions
4 (KERN_WARNING) warning conditions
5 (KERN_NOTICE) normal but significant condition
6 (KERN_INFO) informational
7 (KERN_DEBUG) debug-level messages
log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Format: { n | nk | nM }
n must be a power of two. The default size
is set in the kernel config file.
logo.nologo [FB] Disables display of the built-in Linux logo.
This may be used to provide more screen space for
kernel log messages and is useful when debugging
kernel boot problems.
lp=0 [LP] Specify parallel ports to use, e.g,
lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
lp=reset first parallel port). 'lp=0' disables the
lp=auto printer driver. 'lp=reset' (which can be
specified in addition to the ports) causes
attached printers to be reset. Using
lp=port1,port2,... specifies the parallel ports
to associate lp devices with, starting with
lp0. A port specification may be 'none' to skip
that lp device, or a parport name such as
'parport0'. Specifying 'lp=auto' instead of a
port specification list means that device IDs
from each port should be examined, to see if
an IEEE 1284-compliant printer is attached; if
so, the driver will manage that printer.
See also header of drivers/char/lp.c.
lpj=n [KNL]
Sets loops_per_jiffy to given constant, thus avoiding
time-consuming boot-time autodetection (up to 250 ms per
CPU). 0 enables autodetection (default). To determine
the correct value for your kernel, boot with normal
autodetection and see what value is printed. Note that
on SMP systems the preset will be applied to all CPUs,
which is likely to cause problems if your CPUs need
significantly divergent settings. An incorrect value
will cause delays in the kernel to be wrong, leading to
unpredictable I/O errors and other breakage. Although
unlikely, in the extreme case this might damage your
hardware.
ltpc= [NET]
Format: <io>,<irq>,<dma>
mac5380= [HW,SCSI] Format:
<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
machvec= [IA64] Force the use of a particular machine-vector
(machvec) in a generic kernel.
Example: machvec=hpzx1_swiotlb
machtype= [Loongson] Share the same kernel image file between different
yeeloong laptop.
Example: machtype=lemote-yeeloong-2f-7inch
max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
than or equal to this physical address is ignored.
maxcpus= [SMP] Maximum number of processors that an SMP kernel
should make use of. maxcpus=n : n >= 0 limits the
kernel to using 'n' processors. n=0 is a special case,
it is equivalent to "nosmp", which also disables
the IO APIC.
max_loop= [LOOP] Maximum number of loopback devices that can
be mounted
Format: <1-256>
max_luns= [SCSI] Maximum number of LUNs to probe.
Should be between 1 and 2^32-1.
max_report_luns=
[SCSI] Maximum number of LUNs received.
Should be between 1 and 16384.
mcatest= [IA-64]
mce [X86-32] Machine Check Exception
mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
md= [HW] RAID subsystems devices and level
See Documentation/md.txt.
mdacon= [MDA]
Format: <first>,<last>
Specifies range of consoles to be captured by the MDA.
mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
Amount of memory to be used when the kernel is not able
to see the whole system memory or for test.
[X86-32] Use together with memmap= to avoid physical
address space collisions. Without memmap= PCI devices
could be placed at addresses belonging to unused RAM.
mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
memory.
memchunk=nn[KMG]
[KNL,SH] Allow user to override the default size for
per-device physically contiguous DMA buffers.
memmap=exactmap [KNL,X86] Enable setting of an exact
E820 memory map, as specified by the user.
Such memmap=exactmap lines can be constructed based on
BIOS output or other requirements. See the memmap=nn@ss
option description.
memmap=nn[KMG]@ss[KMG]
[KNL] Force usage of a specific region of memory
Region of memory to be used, from ss to ss+nn.
memmap=nn[KMG]#ss[KMG]
[KNL,ACPI] Mark specific memory as ACPI data.
Region of memory to be used, from ss to ss+nn.
memmap=nn[KMG]$ss[KMG]
[KNL,ACPI] Mark specific memory as reserved.
Region of memory to be used, from ss to ss+nn.
Example: Exclude memory from 0x18690000-0x1869ffff
memmap=64K$0x18690000
or
memmap=0x10000$0x18690000
memory_corruption_check=0/1 [X86]
Some BIOSes seem to corrupt the first 64k of
memory when doing things like suspend/resume.
Setting this option will scan the memory
looking for corruption. Enabling this will
both detect corruption and prevent the kernel
from using the memory being corrupted.
However, its intended as a diagnostic tool; if
repeatable BIOS-originated corruption always
affects the same memory, you can use memmap=
to prevent the kernel from using that memory.
memory_corruption_check_size=size [X86]
By default it checks for corruption in the low
64k, making this memory unavailable for normal
use. Use this parameter to scan for
corruption in more or less memory.
memory_corruption_check_period=seconds [X86]
By default it checks for corruption every 60
seconds. Use this parameter to check at some
other rate. 0 disables periodic checking.
memtest= [KNL,X86] Enable memtest
Format: <integer>
default : 0 <disable>
Specifies the number of memtest passes to be
performed. Each pass selects another test
pattern from a given set of patterns. Memtest
fills the memory with this pattern, validates
memory contents and reserves bad memory
regions that are detected.
meye.*= [HW] Set MotionEye Camera parameters
See Documentation/video4linux/meye.txt.
mfgpt_irq= [IA-32] Specify the IRQ to use for the
Multi-Function General Purpose Timers on AMD Geode
platforms.
mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
the BIOS has incorrectly applied a workaround. TinyBIOS
version 0.98 is known to be affected, 0.99 fixes the
problem by letting the user disable the workaround.
mga= [HW,DRM]
min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
physical address is ignored.
mini2440= [ARM,HW,KNL]
Format:[0..2][b][c][t]
Default: "0tb"
MINI2440 configuration specification:
0 - The attached screen is the 3.5" TFT
1 - The attached screen is the 7" TFT
2 - The VGA Shield is attached (1024x768)
Leaving out the screen size parameter will not load
the TFT driver, and the framebuffer will be left
unconfigured.
b - Enable backlight. The TFT backlight pin will be
linked to the kernel VESA blanking code and a GPIO
LED. This parameter is not necessary when using the
VGA shield.
c - Enable the s3c camera interface.
t - Reserved for enabling touchscreen support. The
touchscreen support is not enabled in the mainstream
kernel as of 2.6.30, a preliminary port can be found
in the "bleeding edge" mini2440 support kernel at
http://repo.or.cz/w/linux-2.6/mini2440.git
mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
parameter allows control of the logging verbosity for
the additional memory initialisation checks. A value
of 0 disables mminit logging and a level of 4 will
log everything. Information is printed at KERN_DEBUG
so loglevel=8 may also need to be specified.
mousedev.tap_time=
[MOUSE] Maximum time between finger touching and
leaving touchpad surface for touch to be considered
a tap and be reported as a left button click (for
touchpads working in absolute mode only).
Format: <msecs>
mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
reporting absolute coordinates, such as tablets
mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
reporting absolute coordinates, such as tablets
movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
is similar to kernelcore except it specifies the
amount of memory used for migratable allocations.
If both kernelcore and movablecore is specified,
then kernelcore will be at *least* the specified
value but may be more. If movablecore on its own
is specified, the administrator must be careful
that the amount of memory usable for all allocations
is not too small.
mpu401= [HW,OSS]
Format: <io>,<irq>
MTD_Partition= [MTD]
Format: <name>,<region-number>,<size>,<offset>
MTD_Region= [MTD] Format:
<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
mtdparts= [MTD]
See drivers/mtd/cmdlinepart.c.
onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
boundary - index of last SLC block on Flex-OneNAND.
The remaining blocks are configured as MLC blocks.
lock - Configure if Flex-OneNAND boundary should be locked.
Once locked, the boundary cannot be changed.
1 indicates lock status, 0 indicates unlock status.
mtdset= [ARM]
ARM/S3C2412 JIVE boot control
See arch/arm/mach-s3c2412/mach-jive.c
mtouchusb.raw_coordinates=
[HW] Make the MicroTouch USB driver use raw coordinates
('y', default) or cooked coordinates ('n')
mtrr_chunk_size=nn[KMG] [X86]
used for mtrr cleanup. It is largest continuous chunk
that could hold holes aka. UC entries.
mtrr_gran_size=nn[KMG] [X86]
Used for mtrr cleanup. It is granularity of mtrr block.
Default is 1.
Large value could prevent small alignment from
using up MTRRs.
mtrr_spare_reg_nr=n [X86]
Format: <integer>
Range: 0,7 : spare reg number
Default : 1
Used for mtrr cleanup. It is spare mtrr entries number.
Set to 2 or more if your graphical card needs more.
n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
NCR_D700= [HW,SCSI]
See header of drivers/scsi/NCR_D700.c.
ncr5380= [HW,SCSI]
ncr53c400= [HW,SCSI]
ncr53c400a= [HW,SCSI]
ncr53c406a= [HW,SCSI]
ncr53c8xx= [HW,SCSI]
netdev= [NET] Network devices parameters
Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
Note that mem_start is often overloaded to mean
something different and driver-specific.
This usage is only documented in each driver source
file if at all.
nf_conntrack.acct=
[NETFILTER] Enable connection tracking flow accounting
0 to disable accounting
1 to enable accounting
Default value depends on CONFIG_NF_CT_ACCT that is
going to be removed in 2.6.29.
nfsaddrs= [NFS]
See Documentation/filesystems/nfsroot.txt.
nfsroot= [NFS] nfs root filesystem for disk-less boxes.
See Documentation/filesystems/nfsroot.txt.
nfs.callback_tcpport=
[NFS] set the TCP port on which the NFSv4 callback
channel should listen.
nfs.cache_getent=
[NFS] sets the pathname to the program which is used
to update the NFS client cache entries.
nfs.cache_getent_timeout=
[NFS] sets the timeout after which an attempt to
update a cache entry is deemed to have failed.
nfs.idmap_cache_timeout=
[NFS] set the maximum lifetime for idmapper cache
entries.
nfs.enable_ino64=
[NFS] enable 64-bit inode numbers.
If zero, the NFS client will fake up a 32-bit inode
number for the readdir() and stat() syscalls instead
of returning the full 64-bit number.
The default is to return 64-bit inode numbers.
nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
when a NMI is triggered.
Format: [state][,regs][,debounce][,die]
nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Format: [panic,][num]
Valid num: 0,1,2
0 - turn nmi_watchdog off
1 - use the IO-APIC timer for the NMI watchdog
2 - use the local APIC for the NMI watchdog using
a performance counter. Note: This will use one
performance counter and the local APIC's performance
vector.
When panic is specified, panic when an NMI watchdog
timeout occurs.
This is useful when you use a panic=... timeout and
need the box quickly up again.
Instead of 1 and 2 it is possible to use the following
symbolic names: lapic and ioapic
Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
netpoll.carrier_timeout=
[NET] Specifies amount of time (in seconds) that
netpoll should wait for a carrier. By default netpoll
waits 4 seconds.
no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
emulation library even if a 387 maths coprocessor
is present.
no_console_suspend
[HW] Never suspend the console
Disable suspending of consoles during suspend and
hibernate operations. Once disabled, debugging
messages can reach various consoles while the rest
of the system is being put to sleep (ie, while
debugging driver suspend/resume hooks). This may
not work reliably with all consoles, but is known
to work with serial and VGA consoles.
noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
caches in the slab allocator. Saves per-node memory,
but will impact performance.
noalign [KNL,ARM]
noapic [SMP,APIC] Tells the kernel to not make use of any
IOAPICs that may be present in the system.
nobats [PPC] Do not use BATs for mapping kernel lowmem
on "Classic" PPC cores.
nocache [ARM]
noclflush [BUGS=X86] Don't use the CLFLUSH instruction
nodelayacct [KNL] Disable per-task delay accounting
nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
nodsp [SH] Disable hardware DSP at boot time.
noefi [X86] Disable EFI runtime services support.
noexec [IA-64]
noexec [X86]
On X86-32 available only on PAE configured kernels.
noexec=on: enable non-executable mappings (default)
noexec=off: disable non-executable mappings
noexec32 [X86-64]
This affects only 32-bit executables.
noexec32=on: enable non-executable mappings (default)
read doesn't imply executable mappings
noexec32=off: disable non-executable mappings
read implies executable mappings
nofpu [SH] Disable hardware FPU at boot time.
nofxsr [BUGS=X86-32] Disables x86 floating point extended
register save and restore. The kernel will only save
legacy floating-point registers on task switch.
noxsave [BUGS=X86] Disables x86 extended register state save
and restore using xsave. The kernel will fallback to
enabling legacy floating-point and sse state.
nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
wfi(ARM) instruction doesn't work correctly and not to
use it. This is also useful when using JTAG debugger.
no-hlt [BUGS=X86-32] Tells the kernel that the hlt
instruction doesn't work correctly and not to
use it.
no_file_caps Tells the kernel not to honor file capabilities. The
only way then for a file to be executed with privilege
is to be setuid root or executed by root.
nohalt [IA-64] Tells the kernel not to use the power saving
function PAL_HALT_LIGHT when idle. This increases
power-consumption. On the positive side, it reduces
interrupt wake-up latency, which may improve performance
in certain environments such as networked servers or
real-time systems.
nohz= [KNL] Boottime enable/disable dynamic ticks
Valid arguments: on, off
Default: on
noiotrap [SH] Disables trapped I/O port accesses.
noirqdebug [X86-32] Disables the code which attempts to detect and
disable unhandled interrupt sources.
no_timer_check [X86,APIC] Disables the code which tests for
broken timer IRQ sources.
noisapnp [ISAPNP] Disables ISA PnP code.
noinitrd [RAM] Tells the kernel not to load any configured
initial RAM disk.
nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
remapping.
nointroute [IA-64]
nojitter [IA64] Disables jitter checking for ITC timers.
nolapic [X86-32,APIC] Do not enable or use the local APIC.
nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
noltlbs [PPC] Do not use large page/tlb entries for kernel
lowmem mapping on PPC40x.
nomca [IA-64] Disable machine check abort handling
nomce [X86-32] Machine Check Exception
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).
norandmaps Don't use address space randomization. Equivalent to
echo 0 > /proc/sys/kernel/randomize_va_space
noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
noreplace-smp [X86-32,SMP] Don't replace SMP instructions
with UP alternatives
noresidual [PPC] Don't use residual data on PReP machines.
noresume [SWSUSP] Disables resume and restores original swap
space.
no-scroll [VGA] Disables scrollback.
This is required for the Braillex ib80-piezo Braille
reader made by F.H. Papenmeier (Germany).
nosbagart [IA-64]
nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
and disable the IO APIC. legacy for "maxcpus=0".
nosoftlockup [KNL] Disable the soft-lockup detector.
noswapaccount [KNL] Disable accounting of swap in memory resource
controller. (See Documentation/cgroups/memory.txt)
nosync [HW,M68K] Disables sync negotiation for all devices.
notsc [BUGS=X86-32] Disable Time Stamp Counter
nousb [USB] Disable the USB subsystem
nowb [ARM]
nox2apic [X86-64,APIC] Do not enable x2APIC mode.
nptcg= [IA64] Override max number of concurrent global TLB
purges which is reported from either PAL_VM_SUMMARY or
SAL PALO.
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
one of ['zone', 'node', 'default'] can be specified
This can be set from sysctl after boot.
See Documentation/sysctl/vm.txt for details.
ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
See Documentation/debugging-via-ohci1394.txt for more
info.
olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
Rather than timing out after 20 ms if an EC
command is not properly ACKed, override the length
of the timeout. We have interrupts disabled while
waiting for the ACK, so if this is set too high
interrupts *may* be lost!
opl3= [HW,OSS]
Format: <io>
oprofile.timer= [HW]
Use timer interrupt instead of performance counters
oprofile.cpu_type= Force an oprofile cpu type
This might be useful if you have an older oprofile
userland or if you want common events.
Format: { arch_perfmon }
arch_perfmon: [X86] Force use of architectural
perfmon on Intel CPUs instead of the
CPU specific event set.
osst= [HW,SCSI] SCSI Tape Driver
Format: <buffer_size>,<write_threshold>
See also Documentation/scsi/st.txt.
panic= [KNL] Kernel behaviour on panic
Format: <timeout>
parkbd.port= [HW] Parallel port number the keyboard adapter is
connected to, default is 0.
Format: <parport#>
parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
0 for XT, 1 for AT (default is AT).
Format: <mode>
parport= [HW,PPT] Specify parallel ports. 0 disables.
Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
Use 'auto' to force the driver to use any
IRQ/DMA settings detected (the default is to
ignore detected IRQ/DMA settings because of
possible conflicts). You can specify the base
address, IRQ, and DMA settings; IRQ and DMA
should be numbers, or 'auto' (for using detected
settings on that particular port), or 'nofifo'
(to avoid using a FIFO even if it is detected).
Parallel ports are assigned in the order they
are specified on the command line, starting
with parport0.
parport_init_mode= [HW,PPT]
Configure VIA parallel port to operate in
a specific mode. This is necessary on Pegasos
computer where firmware has no options for setting
up parallel port mode and sets it to spp.
Currently this function knows 686a and 8231 chips.
Format: [spp|ps2|epp|ecp|ecpepp]
pas2= [HW,OSS] Format:
<io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
pas16= [HW,SCSI]
See header of drivers/scsi/pas16.c.
pause_on_oops=
Halt all CPUs after the first oops has been printed for
the specified number of seconds. This is to be used if
your oopses keep scrolling off the screen.
pcbit= [HW,ISDN]
pcd. [PARIDE]
See header of drivers/block/paride/pcd.c.
See also Documentation/blockdev/paride.txt.
pci=option[,option...] [PCI] various PCI subsystem options:
earlydump [X86] dump PCI config space before the kernel
changes anything
off [X86] don't probe for the PCI bus
bios [X86-32] force use of PCI BIOS, don't access
the hardware directly. Use this if your machine
has a non-standard PCI host bridge.
nobios [X86-32] disallow use of PCI BIOS, only direct
hardware access methods are allowed. Use this
if you experience crashes upon bootup and you
suspect they are caused by the BIOS.
conf1 [X86] Force use of PCI Configuration
Mechanism 1.
conf2 [X86] Force use of PCI Configuration
Mechanism 2.
noaer [PCIE] If the PCIEAER kernel config parameter is
enabled, this kernel boot option can be used to
disable the use of PCIE advanced error reporting.
nodomains [PCI] Disable support for multiple PCI
root domains (aka PCI segments, in ACPI-speak).
nommconf [X86] Disable use of MMCONFIG for PCI
Configuration
check_enable_amd_mmconf [X86] check for and enable
properly configured MMIO access to PCI
config space on AMD family 10h CPU
nomsi [MSI] If the PCI_MSI kernel config parameter is
enabled, this kernel boot option can be used to
disable the use of MSI interrupts system-wide.
noioapicquirk [APIC] Disable all boot interrupt quirks.
Safety option to keep boot IRQs enabled. This
should never be necessary.
ioapicreroute [APIC] Enable rerouting of boot IRQs to the
primary IO-APIC for bridges that cannot disable
boot IRQs. This fixes a source of spurious IRQs
when the system masks IRQs.
noioapicreroute [APIC] Disable workaround that uses the
boot IRQ equivalent of an IRQ that connects to
a chipset where boot IRQs cannot be disabled.
The opposite of ioapicreroute.
biosirq [X86-32] Use PCI BIOS calls to get the interrupt
routing table. These calls are known to be buggy
on several machines and they hang the machine
when used, but on other computers it's the only
way to get the interrupt routing table. Try
this option if the kernel is unable to allocate
IRQs or discover secondary PCI buses on your
motherboard.
rom [X86] Assign address space to expansion ROMs.
Use with caution as certain devices share
address decoders between ROMs and other
resources.
norom [X86] Do not assign address space to
expansion ROMs that do not already have
BIOS assigned address ranges.
irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
assigned automatically to PCI devices. You can
make the kernel exclude IRQs of your ISA cards
this way.
pirqaddr=0xAAAAA [X86] Specify the physical address
of the PIRQ table (normally generated
by the BIOS) if it is outside the
F0000h-100000h range.
lastbus=N [X86] Scan all buses thru bus #N. Can be
useful if the kernel is unable to find your
secondary buses and you want to tell it
explicitly which ones they are.
assign-busses [X86] Always assign all PCI bus
numbers ourselves, overriding
whatever the firmware may have done.
usepirqmask [X86] Honor the possible IRQ mask stored
in the BIOS $PIR table. This is needed on
some systems with broken BIOSes, notably
some HP Pavilion N5400 and Omnibook XE3
notebooks. This will have no effect if ACPI
IRQ routing is enabled.
noacpi [X86] Do not use ACPI for IRQ routing
or for PCI scanning.
use_crs [X86] Use _CRS for PCI resource
allocation.
routeirq Do IRQ routing for all PCI devices.
This is normally done in pci_enable_device(),
so this option is a temporary workaround
for broken drivers that don't call it.
skip_isa_align [X86] do not align io start addr, so can
handle more pci cards
firmware [ARM] Do not re-enumerate the bus but instead
just use the configuration from the
bootloader. This is currently used on
IXP2000 systems where the bus has to be
configured a certain way for adjunct CPUs.
noearly [X86] Don't do any early type 1 scanning.
This might help on some broken boards which
machine check when some devices' config space
is read. But various workarounds are disabled
and some IOMMU drivers will not work.
bfsort Sort PCI devices into breadth-first order.
This sorting is done to get a device
order compatible with older (<= 2.4) kernels.
nobfsort Don't sort PCI devices into breadth-first order.
cbiosize=nn[KMG] The fixed amount of bus space which is
reserved for the CardBus bridge's IO window.
The default value is 256 bytes.
cbmemsize=nn[KMG] The fixed amount of bus space which is
reserved for the CardBus bridge's memory
window. The default value is 64 megabytes.
resource_alignment=
Format:
[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
Specifies alignment and device to reassign
aligned memory resources.
If <order of align> is not specified,
PAGE_SIZE is used as alignment.
PCI-PCI bridge can be specified, if resource
windows need to be expanded.
ecrc= Enable/disable PCIe ECRC (transaction layer
end-to-end CRC checking).
bios: Use BIOS/firmware settings. This is the
the default.
off: Turn ECRC off
on: Turn ECRC on.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
off Disable ASPM.
force Enable ASPM even on devices that claim not to support it.
WARNING: Forcing ASPM on may cause system lockups.
pcmv= [HW,PCMCIA] BadgePAD 4
pd. [PARIDE]
See Documentation/blockdev/paride.txt.
pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
boot time.
Format: { 0 | 1 }
See arch/parisc/kernel/pdc_chassis.c
percpu_alloc= Select which percpu first chunk allocator to use.
Currently supported values are "embed" and "page".
Archs may support subset or none of the selections.
See comments in mm/percpu.c for details on each
allocator. This parameter is primarily for debugging
and performance comparison.
pf. [PARIDE]
See Documentation/blockdev/paride.txt.
pg. [PARIDE]
See Documentation/blockdev/paride.txt.
pirq= [SMP,APIC] Manual mp-table setup
See Documentation/x86/i386/IO-APIC.txt.
plip= [PPT,NET] Parallel port network link
Format: { parport<nr> | timid | 0 }
See also Documentation/parport.txt.
pmtmr= [X86] Manual setup of pmtmr I/O Port.
Override pmtimer IOPort with a hex value.
e.g. pmtmr=0x508
pnp.debug [PNP]
Enable PNP debug messages. This depends on the
CONFIG_PNP_DEBUG_MESSAGES option.
pnpacpi= [ACPI]
{ off }
pnpbios= [ISAPNP]
{ on | off | curr | res | no-curr | no-res }
pnp_reserve_irq=
[ISAPNP] Exclude IRQs for the autoconfiguration
pnp_reserve_dma=
[ISAPNP] Exclude DMAs for the autoconfiguration
pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Ranges are in pairs (I/O port base and size).
pnp_reserve_mem=
[ISAPNP] Exclude memory regions for the
autoconfiguration.
Ranges are in pairs (memory base and size).
ports= [IP_VS_FTP] IPVS ftp helper module
Default is 21.
Up to 8 (IP_VS_APP_MAX_PORTS) ports
may be specified.
Format: <port>,<port>....
print-fatal-signals=
[KNL] debug: print fatal signals
print-fatal-signals=1: print segfault info to
the kernel console.
default: off.
printk.time= Show timing data prefixed to each printk message line
Format: <bool> (1/Y/y=enable, 0/N/n=disable)
processor.max_cstate= [HW,ACPI]
Limit processor to maximum C-state
max_cstate=9 overrides any DMI blacklist limit.
processor.nocst [HW,ACPI]
Ignore the _CST method to determine C-states,
instead using the legacy FADT method
profile= [KNL] Enable kernel profiling via /proc/profile
Format: [schedule,]<number>
Param: "schedule" - profile schedule points.
Param: <number> - step/bucket size as a power of 2 for
statistical time based profiling.
Param: "sleep" - profile D-state sleeping (millisecs).
Requires CONFIG_SCHEDSTATS
Param: "kvm" - profile VM exits.
prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
before loading.
See Documentation/blockdev/ramdisk.txt.
psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
probe for; one of (bare|imps|exps|lifebook|any).
psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
per second.
psmouse.resetafter= [HW,MOUSE]
Try to reset the device after so many bad packets
(0 = never).
psmouse.resolution=
[HW,MOUSE] Set desired mouse resolution, in dpi.
psmouse.smartscroll=
[HW,MOUSE] Controls Logitech smartscroll autorepeat.
0 = disabled, 1 = enabled (default).
pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Format:
<io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
pt. [PARIDE]
See Documentation/blockdev/paride.txt.
pty.legacy_count=
[KNL] Number of legacy pty's. Overwrites compiled-in
default number.
quiet [KNL] Disable most log messages
r128= [HW,DRM]
raid= [HW,RAID]
See Documentation/md.txt.
ramdisk_blocksize= [RAM]
See Documentation/blockdev/ramdisk.txt.
ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
See Documentation/blockdev/ramdisk.txt.
rcupdate.blimit= [KNL,BOOT]
Set maximum number of finished RCU callbacks to process
in one batch.
rcupdate.qhimark= [KNL,BOOT]
Set threshold of queued
RCU callbacks over which batch limiting is disabled.
rcupdate.qlowmark= [KNL,BOOT]
Set threshold of queued RCU callbacks below which
batch limiting is re-enabled.
rdinit= [KNL]
Format: <full_path>
Run specified binary instead of /init from the ramdisk,
used for early userspace startup. See initrd.
reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Format: <reboot_mode>[,<reboot_mode2>[,...]]
See arch/*/kernel/reboot.c or arch/*/kernel/process.c
relax_domain_level=
[KNL, SMP] Set scheduler's default relax_domain_level.
See Documentation/cgroups/cpusets.txt.
reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
reservetop= [X86-32]
Format: nn[KMG]
Reserves a hole at the top of the kernel virtual
address space.
reset_devices [KNL] Force drivers to reset the underlying device
during initialization.
resume= [SWSUSP]
Specify the partition device for software suspend
resume_offset= [SWSUSP]
Specify the offset from the beginning of the partition
given by "resume=" at which the swap header is located,
in <PAGE_SIZE> units (needed only for swap files).
See Documentation/power/swsusp-and-swap-files.txt
retain_initrd [RAM] Keep initrd memory after extraction
rhash_entries= [KNL,NET]
Set number of hash buckets for route cache
riscom8= [HW,SERIAL]
Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
ro [KNL] Mount root device read-only on boot
root= [KNL] Root filesystem
rootdelay= [KNL] Delay (in seconds) to pause before attempting to
mount the root filesystem
rootflags= [KNL] Set root filesystem mount option string
rootfstype= [KNL] Set root filesystem type
rootwait [KNL] Wait (indefinitely) for root device to show up.
Useful for devices that are detected asynchronously
(e.g. USB and MMC devices).
root_plug.vendor_id=
[ROOTPLUG] Override the default vendor ID
root_plug.product_id=
[ROOTPLUG] Override the default product ID
root_plug.debug=
[ROOTPLUG] Enable debugging output
rw [KNL] Mount root device read-write on boot
S [KNL] Run init in single mode
sa1100ir [NET]
See drivers/net/irda/sa1100_ir.c.
sbni= [NET] Granch SBNI12 leased line adapter
sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
Format: <io>[,<timeout>[,<isapnp>]]
scsi_debug_*= [SCSI]
See drivers/scsi/scsi_debug.c.
scsi_default_dev_flags=
[SCSI] SCSI default device flags
Format: <integer>
scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
Format: <vendor>:<model>:<flags>
(flags are integer value)
scsi_logging_level= [SCSI] a bit mask of logging levels
See drivers/scsi/scsi_logging.h for bits. Also
settable via sysctl at dev.scsi.logging_level
(/proc/sys/dev/scsi/logging_level).
There is also a nice 'scsi_logging_level' script in the
S390-tools package, available for download at
http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
discovered. async scans them in kernel threads,
allowing boot to proceed. none ignores them, expecting
user space to do the scan.
security= [SECURITY] Choose a security module to enable at boot.
If this boot parameter is not specified, only the first
security module asking for security registration will be
loaded. An invalid security module name will be treated
as if no module has been chosen.
selinux= [SELINUX] Disable or enable SELinux at boot time.
Format: { "0" | "1" }
See security/selinux/Kconfig help text.
0 -- disable.
1 -- enable.
Default value is set via kernel config option.
If enabled at boot time, /selinux/disable can be used
later to disable prior to initial policy load.
serialnumber [BUGS=X86-32]
shapers= [NET]
Maximal number of shapers.
show_msr= [x86] show boot-time MSR settings
Format: { <integer> }
Show boot-time (BIOS-initialized) MSR settings.
The parameter means the number of CPUs to show,
for example 1 means boot CPU only.
sim710= [SCSI,HW]
See header of drivers/scsi/sim710.c.
simeth= [IA-64]
simscsi=
slram= [HW,MTD]
slub_debug[=options[,slabs]] [MM, SLUB]
Enabling slub_debug allows one to determine the
culprit if slab objects become corrupted. Enabling
slub_debug can create guard zones around objects and
may poison objects when not in use. Also tracks the
last alloc / free. For more information see
Documentation/vm/slub.txt.
slub_max_order= [MM, SLUB]
Determines the maximum allowed order for slabs.
A high setting may cause OOMs due to memory
fragmentation. For more information see
Documentation/vm/slub.txt.
slub_min_objects= [MM, SLUB]
The minimum number of objects per slab. SLUB will
increase the slab order up to slub_max_order to
generate a sufficiently large slab able to contain
the number of objects indicated. The higher the number
of objects the smaller the overhead of tracking slabs
and the less frequently locks need to be acquired.
For more information see Documentation/vm/slub.txt.
slub_min_order= [MM, SLUB]
Determines the mininum page order for slabs. Must be
lower than slub_max_order.
For more information see Documentation/vm/slub.txt.
slub_nomerge [MM, SLUB]
Disable merging of slabs with similar size. May be
necessary if there is some reason to distinguish
allocs to different slabs. Debug options disable
merging on their own.
For more information see Documentation/vm/slub.txt.
smart2= [HW]
Format: <io1>[,<io2>[,...,<io8>]]
smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
attempt to substitute SMP alternatives once at boot.
smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
smsc-ircc2.ircc_sir= [HW] SIR base I/O port
smsc-ircc2.ircc_fir= [HW] FIR base I/O port
smsc-ircc2.ircc_irq= [HW] IRQ line
smsc-ircc2.ircc_dma= [HW] DMA channel
smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
0: Toshiba Satellite 1800 (GP data pin select)
1: Fast pin select (default)
2: ATC IRMode
snd-ad1816a= [HW,ALSA]
snd-ad1848= [HW,ALSA]
snd-ali5451= [HW,ALSA]
snd-als100= [HW,ALSA]
snd-als4000= [HW,ALSA]
snd-azt2320= [HW,ALSA]
snd-cmi8330= [HW,ALSA]
snd-cmipci= [HW,ALSA]
snd-cs4231= [HW,ALSA]
snd-cs4232= [HW,ALSA]
snd-cs4236= [HW,ALSA]
snd-cs4281= [HW,ALSA]
snd-cs46xx= [HW,ALSA]
snd-dt019x= [HW,ALSA]
snd-dummy= [HW,ALSA]
snd-emu10k1= [HW,ALSA]
snd-ens1370= [HW,ALSA]
snd-ens1371= [HW,ALSA]
snd-es968= [HW,ALSA]
snd-es1688= [HW,ALSA]
snd-es18xx= [HW,ALSA]
snd-es1938= [HW,ALSA]
snd-es1968= [HW,ALSA]
snd-fm801= [HW,ALSA]
snd-gusclassic= [HW,ALSA]
snd-gusextreme= [HW,ALSA]
snd-gusmax= [HW,ALSA]
snd-hdsp= [HW,ALSA]
snd-ice1712= [HW,ALSA]
snd-intel8x0= [HW,ALSA]
snd-interwave= [HW,ALSA]
snd-interwave-stb=
[HW,ALSA]
snd-korg1212= [HW,ALSA]
snd-maestro3= [HW,ALSA]
snd-mpu401= [HW,ALSA]
snd-mtpav= [HW,ALSA]
snd-nm256= [HW,ALSA]
snd-opl3sa2= [HW,ALSA]
snd-opti92x-ad1848=
[HW,ALSA]
snd-opti92x-cs4231=
[HW,ALSA]
snd-opti93x= [HW,ALSA]
snd-pmac= [HW,ALSA]
snd-rme32= [HW,ALSA]
snd-rme96= [HW,ALSA]
snd-rme9652= [HW,ALSA]
snd-sb8= [HW,ALSA]
snd-sb16= [HW,ALSA]
snd-sbawe= [HW,ALSA]
snd-serial= [HW,ALSA]
snd-sgalaxy= [HW,ALSA]
snd-sonicvibes= [HW,ALSA]
snd-sun-amd7930=
[HW,ALSA]
snd-sun-cs4231= [HW,ALSA]
snd-trident= [HW,ALSA]
snd-usb-audio= [HW,ALSA,USB]
snd-via82xx= [HW,ALSA]
snd-virmidi= [HW,ALSA]
snd-wavefront= [HW,ALSA]
snd-ymfpci= [HW,ALSA]
softlockup_panic=
[KNL] Should the soft-lockup detector generate panics.
sonypi.*= [HW] Sony Programmable I/O Control Device driver
See Documentation/sonypi.txt
specialix= [HW,SERIAL] Specialix multi-serial port adapter
See Documentation/serial/specialix.txt.
spia_io_base= [HW,MTD]
spia_fio_base=
spia_pedr=
spia_peddr=
sscape= [HW,OSS]
Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
See Documentation/scsi/st.txt.
stacktrace [FTRACE]
Enabled the stack tracer on boot up.
sti= [PARISC,HW]
Format: <num>
Set the STI (builtin display/keyboard on the HP-PARISC
machines) console (graphic card) which should be used
as the initial boot-console.
See also comment in drivers/video/console/sticore.c.
sti_font= [HW]
See comment in drivers/video/console/sticore.c.
stifb= [HW]
Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
sunrpc.min_resvport=
sunrpc.max_resvport=
[NFS,SUNRPC]
SunRPC servers often require that client requests
originate from a privileged port (i.e. a port in the
range 0 < portnr < 1024).
An administrator who wishes to reserve some of these
ports for other uses may adjust the range that the
kernel's sunrpc client considers to be privileged
using these two parameters to set the minimum and
maximum port values.
sunrpc.pool_mode=
[NFS]
Control how the NFS server code allocates CPUs to
service thread pools. Depending on how many NICs
you have and where their interrupts are bound, this
option will affect which CPUs will do NFS serving.
Note: this parameter cannot be changed while the
NFS server is running.
auto the server chooses an appropriate mode
automatically using heuristics
global a single global pool contains all CPUs
percpu one pool for each CPU
pernode one pool for each NUMA node (equivalent
to global on non-NUMA machines)
sunrpc.tcp_slot_table_entries=
sunrpc.udp_slot_table_entries=
[NFS,SUNRPC]
Sets the upper limit on the number of simultaneous
RPC calls that can be sent from the client to a
server. Increasing these values may allow you to
improve throughput, but will also increase the
amount of memory reserved for use by the client.
swiotlb= [IA-64] Number of I/O TLB slabs
switches= [HW,M68k]
sym53c416= [HW,SCSI]
See header of drivers/scsi/sym53c416.c.
sysrq_always_enabled
[KNL]
Ignore sysrq setting - this boot parameter will
neutralize any effect of /proc/sys/kernel/sysrq.
Useful for debugging.
t128= [HW,SCSI]
See header of drivers/scsi/t128.c.
tdfx= [HW,DRM]
test_suspend= [SUSPEND]
Specify "mem" (for Suspend-to-RAM) or "standby" (for
standby suspend) as the system sleep state to briefly
enter during system startup. The system is woken from
this state using a wakeup-capable RTC alarm.
thash_entries= [KNL,NET]
Set number of hash buckets for TCP connection
thermal.act= [HW,ACPI]
-1: disable all active trip points in all thermal zones
<degrees C>: override all lowest active trip points
thermal.crt= [HW,ACPI]
-1: disable all critical trip points in all thermal zones
<degrees C>: override all critical trip points
thermal.nocrt= [HW,ACPI]
Set to disable actions on ACPI thermal zone
critical and hot trip points.
thermal.off= [HW,ACPI]
1: disable ACPI thermal control
thermal.psv= [HW,ACPI]
-1: disable all passive trip points
<degrees C>: override all passive trip points to this
value
thermal.tzp= [HW,ACPI]
Specify global default ACPI thermal zone polling rate
<deci-seconds>: poll all this frequency
0: no polling (default)
tmscsim= [HW,SCSI]
See comment before function dc390_setup() in
drivers/scsi/tmscsim.c.
topology= [S390]
Format: {off | on}
Specify if the kernel should make use of the cpu
topology informations if the hardware supports these.
The scheduler will make use of these informations and
e.g. base its process migration decisions on it.
Default is off.
tp720= [HW,PS2]
trace_buf_size=nn[KMG]
[FTRACE] will set tracing buffer size.
trace_event=[event-list]
[FTRACE] Set and start specified trace events in order
to facilitate early boot debugging.
See also Documentation/trace/events.txt
trix= [HW,OSS] MediaTrix AudioTrix Pro
Format:
<io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
tsc= Disable clocksource-must-verify flag for TSC.
Format: <string>
[x86] reliable: mark tsc clocksource as reliable, this
disables clocksource verification at runtime.
Used to enable high-resolution timer mode on older
hardware, and in virtualized environment.
turbografx.map[2|3]= [HW,JOY]
TurboGraFX parallel port interface
Format:
<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
See also Documentation/input/joystick-parport.txt
u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
See header of drivers/scsi/u14-34f.c.
uart401= [HW,OSS]
Format: <io>,<irq>
uart6850= [HW,OSS]
Format: <io>,<irq>
uhci-hcd.ignore_oc=
[USB] Ignore overcurrent events (default N).
Some badly-designed motherboards generate lots of
bogus events, for ports that aren't wired to
anything. Set this parameter to avoid log spamming.
Note that genuine overcurrent events won't be
reported either.
unknown_nmi_panic
[X86]
Set unknown_nmi_panic=1 early on boot.
usbcore.autosuspend=
[USB] The autosuspend time delay (in seconds) used
for newly-detected USB devices (default 2). This
is the time required before an idle device will be
autosuspended. Devices for which the delay is set
to a negative value won't be autosuspended at all.
usbcore.usbfs_snoop=
[USB] Set to log all usbfs traffic (default 0 = off).
usbcore.blinkenlights=
[USB] Set to cycle leds on hubs (default 0 = off).
usbcore.old_scheme_first=
[USB] Start with the old device initialization
scheme (default 0 = off).
usbcore.use_both_schemes=
[USB] Try the other device initialization scheme
if the first one fails (default 1 = enabled).
usbcore.initial_descriptor_timeout=
[USB] Specifies timeout for the initial 64-byte
USB_REQ_GET_DESCRIPTOR request in milliseconds
(default 5000 = 5.0 seconds).
usbhid.mousepoll=
[USBHID] The interval which mice are to be polled at.
usb-storage.delay_use=
[UMS] The delay in seconds before a new device is
scanned for Logical Units (default 5).
usb-storage.quirks=
[UMS] A list of quirks entries to supplement or
override the built-in unusual_devs list. List
entries are separated by commas. Each entry has
the form VID:PID:Flags where VID and PID are Vendor
and Product ID values (4-digit hex numbers) and
Flags is a set of characters, each corresponding
to a common usb-storage quirk flag as follows:
a = SANE_SENSE (collect more than 18 bytes
of sense data);
c = FIX_CAPACITY (decrease the reported
device capacity by one sector);
h = CAPACITY_HEURISTICS (decrease the
reported device capacity by one
sector if the number is odd);
i = IGNORE_DEVICE (don't bind to this
device);
l = NOT_LOCKABLE (don't try to lock and
unlock ejectable media);
m = MAX_SECTORS_64 (don't transfer more
than 64 sectors = 32 KB at a time);
o = CAPACITY_OK (accept the capacity
reported by the device);
r = IGNORE_RESIDUE (the device reports
bogus residue values);
s = SINGLE_LUN (the device has only one
Logical Unit);
w = NO_WP_DETECT (don't test whether the
medium is write-protected).
Example: quirks=0419:aaf5:rl,0421:0433:rc
vdso= [X86,SH]
vdso=2: enable compat VDSO (default with COMPAT_VDSO)
vdso=1: enable VDSO (default)
vdso=0: disable VDSO mapping
vdso32= [X86]
vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
vdso32=1: enable 32-bit VDSO (default)
vdso32=0: disable 32-bit VDSO mapping
vector= [IA-64,SMP]
vector=percpu: enable percpu vector domain
video= [FB] Frame buffer configuration
See Documentation/fb/modedb.txt.
vga= [BOOT,X86-32] Select a particular video mode
See Documentation/x86/boot.txt and
Documentation/svga.txt.
Use vga=ask for menu.
This is actually a boot loader parameter; the value is
passed to the kernel using a special protocol.
vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
size of <nn>. This can be used to increase the
minimum size (128MB on x86). It can also be used to
decrease the size and leave more room for directly
mapped kernel RAM.
vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
Format: <command>
vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
Format: <command>
vmpoff= [KNL,S390] Perform z/VM CP command after power off.
Format: <command>
vt.default_blu= [VT]
Format: <blue0>,<blue1>,<blue2>,...,<blue15>
Change the default blue palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_grn= [VT]
Format: <green0>,<green1>,<green2>,...,<green15>
Change the default green palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_red= [VT]
Format: <red0>,<red1>,<red2>,...,<red15>
Change the default red palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_utf8=
[VT]
Format=<0|1>
Set system-wide default UTF-8 mode for all tty's.
Default is 1, i.e. UTF-8 mode is enabled for all
newly opened terminals.
waveartist= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>
wd33c93= [HW,SCSI]
See header of drivers/scsi/wd33c93.c.
wd7000= [HW,SCSI]
See header of drivers/scsi/wd7000.c.
wdt= [WDT] Watchdog
See Documentation/watchdog/wdt.txt.
x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
default x2apic cluster mode on platforms
supporting x2apic.
xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
xd_geo= See header of drivers/block/xd.c.
xirc2ps_cs= [NET,PCMCIA]
Format:
<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
______________________________________________________________________
TODO:
Add documentation for ALSA options.
Add more DRM drivers.
----------------------------------------------------------------------------------------------------------------------------------------------
作者：北南南北
来自：LinuxSir.Org
摘要： GRUB是多系统引导管理器，简单的说既能引导Linux，同时也能引导Windows；从LinuxSir.Org 讨论区近四年的观察来看，大多初学者并不能在短时间内掌握GRUB的用法，为了解决初学者在最短时间内掌握GRUB，重写GRUB入门文档还是有必要的；
本文重点介绍了GRUB的menu.lst的写法，另外通过GRUB命令行引导系统也做了详述；这些无论是对Windows版本的WINGRUB还是Linux版本的GRUB都是适用的；
目录索引
一、什么是多重操作系统引导管理器，什么是GRUB；
1、什么是多重操作系统引导管理器及工作原理；
2、什么是GRUB；为什么我要选择GRUB；
1）什么是GRUB；
2）“GRUB太不好用”──对GRUB的认识的误区；
3）为什么要选择GRUB；
二、GRUB软件包版本选择和安装；
1、Linux版本的GRUB及Windows版本的GRUB的说明；
2、GRUB的Windows版本WINGRUB；
3、GRUB的Linux版本软件包的安装；
三、在Linux中，GRUB的配置中的安装和写入硬盘的MBR；
1、在Linux中，GRUB配置过程中的安装grub-install；
2、设定GRUB的/boot分区并写入MBR；
四、GRUB的配置文件的menu.lst的写法；
1、menu.lst的写法之一；
1）在menu.lst中 ，通过 root (hd[0-n],y)来指定/boot 所在的分区；
2）在menu.lst中，kernel 命令行的写法；
3）initrd 命令行的写法；
4）menu.lst第一种写法的总结和实践；
1］用fdisk -l ；df -lh ；more /etc/fstab来确认分区情况；
2］查看内核vmlinuz的和initrd文件名的全称；
3］开始写menu.lst ；
2、menu.lst的写法之二，精简型；
1）第一种情况：/boot和Linux的/根分区在同一个分区；
2）第二种情况：/boot独立一个分区，和Linux的根分区不位于同一分区；
五、通过GRUB命令行来启动Linux操作系统；
1、为什么需要学习GRUB的命令行；
2、用命令行来引导Linux操作系统的步骤；
1）进入GRUB的命令行模式 grub>
2）获取帮助GRUB的 help
3）cat的用法；
4）root (hd[0-n,y) 指令来指定/boot所在的分区；
5）kernel 指令，用来指定Linux的内核，及/所在的分区；
6）initrd 命令行来指定initrd文件；
7）boot 引导系统；
8）引导Linux系统实例全程回放；
六、通过GRUB引导Windows操作系统；
1、通过编辑 menu.lst 来引导Windows 系统；
2、通过GRUB指令来引导Windows ；
七、GRUB丢失或损坏的应对策略；
1、由于重新安装Windows或其它未知原因而导致GRUB的丢失；
2、如果出现GRUB提示符，而不出现GRUB的菜单，如何引导系统；
八、关于GRUB的未尽事宜；
九、关于本文；
十、参考文档；
十一、相关文档；
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
正文
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
一、什么是多重操作系统引导管理器，什么是GRUB；
1、什么是多重操作系统引导管理器及工作原理；
系统启动引导管理器，是在计算机启动后运行的第一个程序，他是用来负责加载、传输控制到操作系统的内核，一旦把内核挂载，系统引导管理器的任务就算完成退出，系统引导的其它部份，比如系统的初始化及启动过程则完全由内核来控制完成；
Briefly, boot loader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the operating system kernel software (such as the Hurd or the Linux). The kernel, in turn, initializes the rest of the operating system (e.g. GNU).
在X86 架构的机器中，Linux、BSD 或其它Unix类的操作系统中GRUB、LILO 是大家最为常用，应该说是主流；
Windows 也有类似的工具NTLOADER；比如我们在机器中安装了Windows 98后，我们再安装一个Windows XP ，在机器启动的会有一个菜单让我们选择进入是进入Windows 98 还是进入Windows XP。NTLOADER就是一个多系统启动引导管理器，NTLOADER 同样也能引导Linux，只是极为麻烦罢了；
在Powerpc 架构的机器中，如果安装了Linux的Powerpc 版本，大多是用yaboot 多重引导管理器，比如Apple机目前用的是IBM Powerpc处理器，所以在如果想在Apple机上，安装Macos 和Linux Powerpc 版本，大多是用yaboot来引导多个操作系统；
因为目前X86架构的机器仍是主流， 所以目前GRUB和LILO 仍然是我们最常用的多重操作系统引导管理器；
2、什么是GRUB；为什么我要选择GRUB；
1）什么是GRUB；
GNU GRUB 是一个多重操作系统启动管理器。GNU GRUB 是由GRUB（GRand Unified Bootloader） 派生而来。GRUB 最初由Erich Stefan Boleyn 设计和应用；
GNU GRUB is a Multiboot boot loader. It was derived from GRUB, GRand Unified Bootloader, which was originally designed and implemented by Erich Stefan Boleyn.
2）“GRUB太不好用”──对GRUB的认识的误区；
GRUB真的不好用吗？不是的，通过LinuxSir.Org 社区近四年来的运行，我发现了大多新手弟兄还是不太了解GRUB；当然这也有中文Linux社区的责任，虽然也有GRUB的中文译本，初学Linux的弟兄可能有点看不懂；
我 们欣喜的看到LinuxSir.Org 社区的好多弟兄都曾经或正在写GRUB实践文档，也有的弟兄也总结了GRUB的一些基础知识，比如 probing兄弟的 《GRUB 学习笔记》；由于每个人的写文档时风格不同，可能同一份文档不同的人来写就有不同的风格；所以今天也抖胆也一篇入门级的教程，由于北南不会写高级教程，所 以还得请高手弟兄指教，先谢过；
3）为什么要选择GRUB；
基于在X86架构的CPU而开发操作系统，系统引导管理器不仅仅有GRUB ，而且也有LILO，但对于多重系统引导管理器，你只能选择其一而用；不能两个同时使用；
目前这两个多重系统引导管理器是大家最常用的，也是主流Linux发行版而采用的；有的弟兄喜欢GRUB，比如我个人，有的弟兄喜欢LILO ，比如etony兄（谁是etony，请参见 http://debian.linuxsir.org ）；
主流发行版 Fedora、Redhat、Centos等基于RPM包的系统，在最新版本中都默认GRUB引导；Slackware 目前仍采用LILO；而Debian发行版目前最新的版本也是采用GRUB；
从目前看来，GRUB有逐渐取代LILO之势，GRUB 2.0正在开发之中；所以我们有理由用GRUB，我也有理由写GRUB使用教程；
二、GRUB软件包版本选择和安装；
1、GRUB的版本选择，Linux版本的GRUB及Windows版本的GRUB的说明；
GRUB不但有Linux版本，也有Windows版本；现我们一一介绍；
如 前面所说，目前在在Unix类的操作系统中，大多是都有GRUB；GRUB几乎能引导所有X86架构的操作系统；功能之强，使用简单是GRUB最大的卖 点；由于Windows 操作系统的先入为主的优势，使得大家对Windows的NTLOADER了解的比较多，而对开源社区的GRUB显得有点寞生，由此而带来使用上的“心理恐 惧”；究其初学者对GRUB“恐惧”的主要原因还是对GRUB没有太多的了解和深入；无论是WINGRUB还是Linux版本的GRUB，最方便的还是对 GRUB命令行的操作；一谈到命令行（Command）的操作，可能初学者对此恐惧；其实没有什么难的，象北南这样低级的写手，还能操作得起来，您也应该 能行；
2、GRUB的Windows版本WINGRUB；
请参考：《以WINGRUB 引导安装Fedora 4.0 为例，详述用WINGRUB来引导Linux的安装》
3、GRUB的Linux版本软件包的安装；
其实对于Linux的GRUB，几乎所有的Linux主流发行版都有打包，如果您安装了Linux，并且在开机后出现GRUB字样的，证明您已经安装了GRUB；而无需再次安装；Linux的GRUB软件包安装部份并不是本文的重点；
如果您的Linux系统没有安装GRUB，或者采用的是LILO，而您想用GRUB，可以用系统安装盘自带GRUB软件包来安装，或者到相关发行版本的软件仓库下载后安装；
GRUB 的Linux版本目前在各大发行版中都有打包；比如Fedora/Redhat/Centos/Mandrive/Mandriva/SuSE等以RPM包管理机制的系统，可以通过如下的命令来安装；
请参考《Fedora / Redhat 软件包管理指南》
[root@localhost ~]# rpm -ivh grub*.rpm
如果是Slackware 您可以用如下的办法来安装；
[root@localhost ~]# installpkg grub*.tgz
其它的发行版本请用其自己特色的软件包管理工具来安装；
当然您也可以通过源码包，在任何Linux的发行版上安装；至于源码包的安装方法；
请参考：《如何编译安装源码包软件》
[root@localhost ~]#tar zxvf grub*.tar.gz
[root@localhost ~]#cd grub-xxx
[root@localhost ~]#./configure;make;make install
确认您是否成功安装了GRUB，您可以测试是否有如下两个命令；
[root@localhost ~]# grub
[root@localhost ~]# grub-install
如果您不能找到这两个命令，可能您的可执行程序的路径没有设置；
请参考：《设置可执行程序路径》，当然您可以用绝对路径；比如下面的；
[root@localhost ~]# /usr/sbin/grub
[root@localhost ~]# /usr/sbin/grub-install
如果您还是找不到GRUB软件包安装在哪了；您可以用下面的命令来解决和查找；
[root@localhost ~]# updatedb 注：这个要花很长时间；是索引slocate 的库，然后再通过locate来查找；
[root@localhost ~]# locate grub
比如找到的是有类似如下的；
[root@localhost ~]# locate grub
/sbin/grub-md5-crypt
/sbin/grub
/sbin/grub-install
/sbin/grub-terminfo
在一般情况下，在路径中带有bin或sbin中字样的，这些路径下都是可执行程序；sbin 是超级权限用户才能使用的管理命令；要使用这些命令一般的情况下得切换到root用户下才能使用；比如
[beinan@localhost ~]$ su - 注：切换到root用户，并且切换到其家目录；
Password:
[root@localhost ~]#/sbin/grub 注：用绝对路径来运行grub命令；
三、在Linux中，GRUB的配置中的安装和写入硬盘的MBR；
1、在Linux中，GRUB配置过程中的安装grub-install；
grub-install 命令有何用呢？其实就是把我们前面已经安装的软件包中的一些文件复制到 /boot/grub中；对于新安装GRUB软件包后，也是一个必经的过程；我们前面所说的GRUB软件包的安装；而现在我们说的是GRUB配置的过程中 的安装；虽然在洋文中都是install ，但表达的意思是不一样的；
我们首先要运行 fdisk -l 来确认到底是硬盘的标识；
这个过程主要是确认硬盘的标识是哪个调备，到底是/dev/hda还是/dev/hdb 还是其它的；
[root@localhost ~]# fdisk -l
Disk /dev/hda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hda1 * 1 970 7791493+ 7 HPFS/NTFS
/dev/hda2 971 9729 70356667+ 5 Extended
/dev/hda5 971 2915 15623181 b W95 FAT32
/dev/hda6 2916 4131 9767488+ 83 Linux
/dev/hda7 4132 5590 11719386 83 Linux
/dev/hda8 5591 6806 9767488+ 83 Linux
/dev/hda9 6807 9657 22900626 83 Linux
/dev/hda10 9658 9729 578308+ 82 Linux swap / Solaris
如果通过fdisk -l 出现有/dev/hda字样的，我们就要用下面的命令来安装；
[root@localhost ~]# grub-install /dev/hda
Installation finished. No error reported.
This is the contents of the device map /boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.
(fd0) /dev/fd0
(hd0) /dev/hda
如果是您fdisk -l 出现的有/dev/hdb呢，那就如下运行；
[root@localhost ~]# grub-install /dev/hdb
如果既有/dev/hda和/dev/hdb 就安装到/dev/hda中；
[root@localhost ~]# grub-install /dev/hda
值得注意的是如果您有一个/boot分区，应该用如下的办法来安装；
[root@localhost ~]#grub-install --root-directory=/boot /dev/hda
[root@localhost ~]#grub-install --root-directory=/boot /dev/hdb
注解：具体是/dev/hda还是/dev/hdb，请以fdisk -l 为准；如果两个都有，就看您把/boot分区是放在第一块硬盘还是第二块硬盘上了，以实际情况为准；
2、设定GRUB的/boot分区并写入MBR；；
在Linux中，GRUB软件包的安装，及在配置过程中安装grub到 /boot中还是不够的， 还要把GRUB，写入MBR才行；有时我们重新安装了Windows，Windows会把MBR 重写，这样GRUB就消失了；如果您出现这样的情况，就要进行这个过程；
[root@localhost ~]# grub
会出现grub>提示符，这是grub命令行模式 ，如果能在开机中出现提示符，没有引导不起来的系统，除非您的系统破坏的极为严重。如果仅仅是GRUB被破坏了，GRUB命令行是能让操作系统引导起来的；
接着看例子，我们要找到 /boot/grub/stage1的，在grub>后面输入；
grub> find /boot/grub/stage1
(hd0,6)
(fd0) 注：这个是软驱；现在很少用软驱了，如果您有这方面的需要，自己看GRUB的DOC吧；
注解：
(hd0,6) 这是/boot所在的分区；不要误解为是Linux 的/所在的分区，这是值得注意的；
(fd0) 注：这个是软驱；现在很少用软驱了，如果您有这方面的需要，自己看GRUB的DOC吧；
grub>root (hd0,6) 注：这是/boot所在的分区；
grub>setup (hd0) 注：把GRUB写到MBR上；
注解：
上面这步骤是根据 find /boot/stage1而来的，仔细看一下就明白了；现在我们一般安装很少会把/boot分区列为一个单独的分区；不过有的弟兄可能也喜欢这么做；所以还是有必要说一下为好；
四、GRUB的配置文件的menu.lst的写法；
对 于GRUB来说，如果没有配置menu.lst，无论是Linux版本的GRUB，还是WINGRUB，都会有命令行可用，通过命令行是一样能把操作系统 引导起来的；有些弟兄总以为menu.lst 配置错了， 或者在机器启动后出现grub>命令行模式就要重新安装系统，其实根本没有这个必要；只要学会GRUB的命令行的用法，根本没有必要重装系统；
menu.lst 位于/boot/grub目录中，也就是/boot/grub/menu.lst 文件；您可以用vi或您喜欢的编辑器来编辑他；如果您不会用vi，还是去学习一下吧；简单的用法怎么也得会，对不对？毕竟这个文档不是讲vi的用法的；
有的弟兄会说，我没有menu.lst怎么办？那就创建一个；用下面的命令；
[root@localhost ~]# touch /boot/grub/menu.lst
然后我们再做一个/boot/grub/menu.lst 的链接 /boot/grub/grub.conf
[root@localhost ~]# cd /boot/grub
[root@localhost ~]# ln -s menu.lst grub.conf
现在我们来写GRUB的menu.lst了，因为/boot/grub/grub.conf是 /boot/grub/menu.lst的链接文件，改哪个都行。链接文件相当于Windows的快捷方式，这样可能能更好的理解；
1、menu.lst的写法之一；
首先我们看一下我的Fedora 4.0 中的/boot/grub/menu.lst 的内容；
default=0
timeout=5
#splashimage=(hd0,6)/boot/grub/splash.xpm.gz
hiddenmenu
title Fedora Core (2.6.11-1.1369_FC4)
root (hd0,6)
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
initrd /boot/initrd-2.6.11-1.1369_FC4.img
title WinXp
rootnoverify (hd0,0)
chainloader +1
注解：
default=0
default=0 是默认启动哪个系统，从0开始；每个操作系统的启动的定义都从title开始的，第一个title 在GRUB的启动菜单上显示为0,第二个启动为1，以此类推；
timeout=5
注：表示在开机后，GRUB画面出现几秒后开始以默认启动；如果在启动时，移动上下键，则解除这一规则；
#splashimage=(hd0,6)/boot/grub/splash.xpm.gz 注：GRUB的背景画面，这个是可选项；我不喜欢GRUB的背景画面，所以加#号注掉，也可以删除；
hiddenmenu
注解：隐藏GRUB的启动菜单，这项也是可选的，也可以用#号注掉；
一般的情况下对Linux操作系统的启动，一般要包括四行；title 行；root行；kernel 行；initrd 行；
1）在menu.lst中 ，通过 root (hd[0-n],y)来指定/boot 所在的分区；
title XXXXX 注：title 后面加一个空格，title 是小写的，后面可以自己定义；比如FC4，自己定义一个名字就行；
root (hd[0-n],y) ，在本例中，我们看到的是root (hd0,6) ,root (hd[0-n],y)表示的是/boot所在的分区；有时我们安装Linux的时候，大多是不设置/boot的，这时/boot和/所在的同一个分区； 这个root (hd[0-n],y)很重要，因为/boot目录中虽然有grub目录，最为重要的是还有kernel 和initrd文件，这是Linux能启动起来最为重要东西；
有的弟兄会问，root (hd[0-n],y)是怎么来的？
请参考：《在Linux系统中存储设备的两种表示方法》
2）在menu.lst中，kernel 命令行的写法；
kernel 一行，是通指定内核及Linux的/分区所在位置；
比如例子中是；
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
在这里以kernel 起始，指定Linux的内核的文件所处的绝对路径；因为内核是处在/boot目录中的， 如果/boot是独立的一个分区，则需要把boot省略；如果/boot是独立的分区，这行要写成:
kernel /vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
因 为/boot所处的分区已经在title 下一行root (hd[0-n],y)中指定了，所以就无需要再指明内核处在哪个分区了；另外Linux系统的硬盘分区的挂载配置文件在/etc/fstab ，原理是通过 mount /dev/hd[a-z]X /boot 来进行的；您可以对照着来理解；
ro 表示只读； root=LABEL=/ 来表示Linux的根所处的分区。LABEL=/ 这是硬盘分区格式化为相应文件系统后所加的标签；如果您不了解什么是标签，也可以直接以/dev/hd[a-z]X 或者/dev/sd[a-z]X来表示；就看您的Linux是根分区是在哪个分区了。比如我的是在/dev/hda7 ， 那这里就可以写成root=/dev/hda7；
如果查看系统运行所挂载的分区，请用 df -lh 来查看，就能明白是不是/boot是独立的分区，或者查看/etc/fstab也能知道；
[root@localhost ~]# df -lh
Filesystem 容量 已用 可用 已用% 挂载点
/dev/hda7 11G 9.2G 1.2G 90% /
/dev/shm 236M 0 236M 0% /dev/shm
在这个例子中，我们可以发现 /boot并没有出现只有/dev/hda7，这表示/boot并不是独立的一个分区；所有的东西都包含在/中；于是我们在/boot中查看内核版本；
[root@localhost ~]# ls /boot/vmlinuz*
/boot/vmlinuz-2.6.11-1.1369_FC4 注：看到内核vmlinuz所处的目录；
于是我们就可以这样kernel 这行了；
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
3）initrd 命令行的写法；
如果是/boot独立一个分区，initrd 一行要把/boot中省略；如果/boot不是处于一个分区，而是和Linux的/分区处于同一分区，不应该省略；
比如我们在2）中用的例子；现在拿到这里，我们应该首先查看 /boot中的initrd的文件名到底是什么；
[root@localhost ~]# ls /boot/initrd*
/boot/initrd-2.6.11-1.1369_FC4.img
如果是通过df -lh 得知或查看/etc/fstab 也行， 得知/boot是独立的分区；这时initrd 应该写成；
initrd /initrd-2.6.11-1.1369_FC4.img
如果是 /boot不是独处一个分区，而是在/同一处一个分区， 则要写成；
initrd /boot/initrd-2.6.11-1.1369_FC4.img
4）menu.lst第一种写法的总结和实践；
在这里，我们只说重要的，不重要的就一带而过了；
1］用fdisk -l ；df -lh ；more /etc/fstab来确认分区情况；
我们过fdisk -l ；df -lh ; more /etc/fstab 来确认/boot所在的分区，及Linux的根分区所在位置；
比如我们确认/boot和Linux的/分区同处一个分区；
[root@localhost ~]# df -lh
Filesystem 容量 已用 可用 已用% 挂载点
/dev/hda7 11G 9.2G 1.2G 90% /
/dev/shm 236M 0 236M 0% /dev/shm
然后我们/etc/fstab 中,查看/分所在的分区或分区标签是什么；
[root@localhost ~]# more /etc/fstab
# This file is edited by fstab-sync - see 'man fstab-sync' for details
LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0
/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,managed 0 0
经 过上面的df -lh 和more /etc/fstab 的对照中得知，/boot并是独处一个分区，而是和/在同一个分区；这个Linux系统安装在/dev/hda7上，文件系统（此分区）的标签为 LABEL=/ ，/boot也是处于/dev/hda7 ，/dev/hda7也可以说是 root (hd0,6)；
2]查看内核vmlinuz的和initrd文件名的全称；
[root@localhost ~]# ls -lh /boot/vmlinuz*
-rw-r--r-- 1 root root 1.6M 2005-06-03 /boot/vmlinuz-2.6.11-1.1369_FC4
[root@localhost ~]# ls -lh /boot/initrd*
-rw-r--r-- 1 root root 1.1M 11月 26 22:30 /boot/initrd-2.6.11-1.1369_FC4.img
3]开始写menu.lst ；
我们根据上面所提到的，可以写成如下的样子；
default=0
timeout=5
title FC4
root (hd0,6)
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
initrd /boot/initrd-2.6.11-1.1369_FC4.img
也可以写成；
default=0
timeout=5
title FC4
root (hd0,6)
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
initrd /boot/initrd-2.6.11-1.1369_FC4.img
注解：上面两个不同之处在于一指定Linux的根/所在的分区时，一个是用了文件系统的标签，另一个没有用标签；
2、menu.lst的写法之二，精简型；
本写法主要是把指定/boot所位于的所分区直接写入kernel 指令行；这样就省略了通过root (hd[0-n],y)来指定/boot所位于的分区；
1)第一种情况：/boot和Linux的/根分区在同一个分区；
有前面的那么多的讲解，menu.lst写法之二就好理解多了；也得分两种情况，咱们先把/boot并不是独处一个分区，而是和Linux的根分区处于同一个分区；我们以 4）menu.lst第一种方法的写法总结 的实例为例子；
default=0
timeout=5
title FC4x
kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
initrd (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img
注解：
title FC4x 注：自己为这个Linux 起个简单的名，以title开头，然后一个空格，后面就自己发挥吧，FC4或FC4x都行；
kernel 空格 (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 空格 ro 空格 root=/dev/hda7
kernel 这行这样理解 kernel (boot所在的分区)/boot/内核文件件全称 ro root=Linux根所位于的分区或标签
initrd 空格 (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img
initrd 这行可以这样理解 initrd (/boot所在的分区)/boot/内核文件名全称
2）第二种情况：/boot独立一个分区，和Linux的根分区不是同一个分区；
比如我们查看到df -lh 得到的是
[root@localhost ~]# df -lh
Filesystem 容量 已用 可用 已用% 挂载点
/dev/hda6 200M 120M 80M 60% /boot
/dev/hda7 11G 9.2G 1.2G 90% /
我们再进一行查看/etc/fstab 得知；
LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
所以我们应该写成如下的；
title FC4x
kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img
因为Linux的根分区是/dev/hda7，通过/etc/fstab和df -h的内容得知标签为 LABEL=/的分区就是/dev/hda7 ，所以有；
title FC4x
kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img
五、通过GRUB命令行来启动Linux操作系统；
GRUB的命令行才是王道，如果知道怎么用命令行来启动操作系统，那理解menu.lst的写法也不难；也就是说在开机的时候，不用GRUB的菜单，通过GRUB的命令也是一样能把操作系统引导起来。
因为menu.lst的内容就是GRUB的一个一个的指令集合；是不是Linux这玩意很神奇？
1、为什么需要学习GRUB的命令行；
当 我们把GRUB的menu.lst写错的时候，或者丢掉了menu.lst的时，比如在开机的时候，GRUB会出现grub>类似的命令提示符，这 时需要我们用命令行启动系统；当然您可以不用定义GRUB的菜单 ，直接用命令行来启动系统，比如我现在就是，为了写GRUB的文档，就把menu.lst 删除了，直接用命令来启动系统；
2、用命令行来引导Linux操作系统的步骤；
通过命令行来引导操作系统的流程，也没有什么难的；无非是把指令手工输入到grub>提示符的后面；在这个过程中，tab键的命令补齐功能就显得很重要了。如果您不知道有哪些命令，可以输入help；
1）进入GRUB的命令行模式 grub>
如 果开机时，GRUB出现的是grub>，说明你没有/etc/grub/menu.lst ，您需要自己写一个才会GRUB的菜单，让我们来选择进入哪个系统。如果有GRUB的菜单，您可以按Ctrl+c组合键进入GRUB的命令行模式，会出现 grub> 提示符；
grub>
2）获取帮助GRUB的 help
只要您在grub>提示符的后面输入help 就能得到GRUB所有的命令提示；
grub> help
blocklist FILE boot
cat FILE chainloader [--force] FILE
clear color NORMAL [HIGHLIGHT]
configfile FILE device DRIVE DEVICE
displayapm displaymem
find FILENAME geometry DRIVE [CYLINDER HEAD SECTOR [
halt [--no-apm] help [--all] [PATTERN ...]
hide PARTITION initrd FILE [ARG ...]
kernel [--no-mem-option] [--type=TYPE] makeactive
map TO_DRIVE FROM_DRIVE md5crypt
module FILE [ARG ...] modulenounzip FILE [ARG ...]
pager [FLAG] partnew PART TYPE START LEN
parttype PART TYPE quit
reboot root [DEVICE [HDBIAS]]
rootnoverify [DEVICE [HDBIAS]] serial [--unit=UNIT] [--port=PORT] [--
setkey [TO_KEY FROM_KEY] setup [--prefix=DIR] [--stage2=STAGE2_
terminal [--dumb] [--no-echo] [--no-ed terminfo [--name=NAME --cursor-address
testvbe MODE unhide PARTITION
uppermem KBYTES vbeprobe [MODE]
如果需要得到某个指令的帮助，就在 help 后面空一格，然后输入指令，比如；
grub>help kernel
3）cat的用法；
cat 指令是用来查看文件内容的，有时我们不知道Linux的/boot分区，以及/根分区所在的位置，要查看/etc/fstab的内容来得知，这时，我们就 要用到cat (hd[0-n],y)/etc/fstab 来获得这些内容；注意要学会用tab键命令补齐的功能；
grub> cat ( 按tab 键会出来hd0或hd1之类的；
grub> cat (hd0, 注：输入hd0,然后再按tab键；会出来分区之类的；
grub> cat (hd0,6)
Possible partitions are:
Partition num: 0, Filesystem type unknown, partition type 0x7
Partition num: 4, Filesystem type is fat, partition type 0xb
Partition num: 5, Filesystem type is reiserfs, partition type 0x83
Partition num: 6, Filesystem type is ext2fs, partition type 0x83
Partition num: 7, Filesystem type unknown, partition type 0x83
Partition num: 8, Filesystem type is reiserfs, partition type 0x83
Partition num: 9, Filesystem type unknown, partition type 0x82
grub> cat (hd0,6)/etc/fstab 注：比如我想查看一下 (hd0,6)/etc/fstab的内容就这样输入；
LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0
/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,
managed 0 0
有的弟兄可能会说，我不知道Linux安装在了哪个分区。那根据文件系统来判断一个一个的尝试总可以吧我；只要能cat出/etc/fstab就能为以后引导带来方便；
主 要查看/etc/fstab中的内容，主要是Linux的/分区及/boot是否是独立的分区；如果没有/boot类似的行，证明/boot和Linux 的/处于同一个硬盘分区；比如上面的例子中LABEL=/ 这行是极为重要的；说明Linux系统就安在标签为LABEL=/的分区中；
如果您的Linux系统/boot和/没有位于同一个分区，可能cat (hd[a-n],y) 查到的是类似下面的；
LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
4） root (hd[0-n,y) 指令来指定/boot所在的分区；
其实这个root (hd[0,n],y)是可以省略的，如果省略了，我们要在kerenl 命令中指定；我们前面已经说过 (hd[0-n],y) 硬盘分区的表示方法的用途；主要是用来指定 /boot所在的分区；
比如我们确认/boot和 (hd0,6)，所以就可以这样来输入root (hd0,6)
grub> root (hd0,6)
如果发现不对，可以重新来过；没有什么大不了的；
5） kernel 指令，用来指定Linux的内核，及/所在的分区；
kernel 这个指令可能初学者有点怕，不知道内核在哪个分区，及内核文件名的全称是什么。不要忘记tab键的命令补齐的应用；
如果我们已经通过root (hd[0-n],y) 指定了/boot所在的分区，语法有两个：
如果/boot和Linux的/位于同一个分区，应该是下面的一种格式；
kernel /boot/vmlinuz在这里按tab键来补齐，就看到内核全称了 ro root=/dev/hd[a-z]X
如果/boot有自己独立的分区，应该是；
kernel /vmlinuz在这里按tab键来补齐，就看到内核全称了 ro root=/dev/hd[a-z]X
在这里 root=/dev/hd[a-z]X 是Linux 的/根所位于的分区，如果不知道是哪个分区，就用tab出来的来计算，一个一个的尝试；或用cat (hd[0-n],y)/etc/fstab 中得到Linux的/所在的分区或分区的标签；
grub> kernel /boot/在这里按tab键；这样就列出/boot中的文件了；
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369
_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4 grubBAK memtest86+-1.55
.1 xen-syms xen.gz
grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
[Linux-bzImage, setup=0x1e00, size=0x18e473]
注解： root=LABEL=/ 是Linux的/所在的分区的文件系统的标签；如果您知道Linux的/在哪个具体的分区，用root=/dev/hd[a-z]X来指定也行。比如下面的一行也是可以的；
grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
也可以把/boot所在的分区的指定 root (hd[0-n],y)这行省掉，直接在kernel 中指定/boot所在的分区；所以就在下面的语法；
如果是/boot和Linux的根同处一个分区；
kernel (hd[0-n],y)/boot/vmlinuz ro root=/dev/hd[a-z]X
比如：
grub>kernel
如果是/boot和Linux所在的根不在一个分区；则是；
kernel (hd[0-n],y)/vmlinuz ro root=/dev/hd[a-z]X
grub> kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
[Linux-bzImage, setup=0x1e00, size=0x18e473]
或下面的输入，以cat 出/etc/fstab内容为准；
grub> kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
[Linux-bzImage, setup=0x1e00, size=0x18e473]
6）initrd 命令行来指定initrd文件；
grub> initrd /boot/initrd在这里tab 来补齐；
grub> initrd /boot/initrd-2.6.11-1.1369_FC4.img
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]
如果/boot是独立的一个分区，应该是如下样子的语法；比如下面的；
grub> initrd /initrd在这里tab 来补齐；
grub> initrd /initrd-2.6.11-1.1369_FC4.img
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]
7）boot 引导系统；
grub>boot
前面的几个步骤都弄好 。就进入引导；尝试一下就知道了。。
8）引导Linux系统实例全程回放；
实例：/boot和Linux的/处于同一个硬盘分区；
grub> cat (hd0,6)/etc/fstab
# This file is edited by fstab-sync - see 'man fstab-sync' for details
LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0
/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,managed 0 0
grub> root (hd0,6)
Filesystem type is ext2fs, partition type 0x83
grub> kernel /boot/在这里按tab补齐，全列出/boot所有的文件；
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4
memtest86+-1.55.1 xen-syms xen.gz
grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7 注：输入
[Linux-bzImage, setup=0x1e00, size=0x18e473]
grub> initrd /boot/在这里按tab补齐
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4
memtest86+-1.55.1 xen-syms xen.gz
grub> initrd /boot/initrd-2.6.11-1.1369_FC4.img 注;输入intrd文件名的全名；
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]
grub> boot
我们指定Linux的根时，可以用cat出来的fstab的内容中Linux的/分区文件系统标签来替代；也就是kernel 那行中 root=/dev/hd[a-z]X；
grub> cat (hd0,6)/etc/fstab
# This file is edited by fstab-sync - see 'man fstab-sync' for details
LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0
/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,managed 0 0
grub> root (hd0,6)
Filesystem type is ext2fs, partition type 0x83
grub> kernel /boot/在这里按tab补齐，全列出/boot所有的文件；
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4
memtest86+-1.55.1 xen-syms xen.gz
grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
[Linux-bzImage, setup=0x1e00, size=0x18e473]
grub> initrd /boot/在这里按tab补齐
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4 grubBAK
memtest86+-1.55.1 xen-syms xen.gz
grub> initrd /boot/initrd-2.6.11-1.1369_FC4.img 注;输入intrd文件名的全名；
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]
grub> boot
如果是/boot和Linux的根分区不在同一个分区，要把kernel和initrd 指令中的/boot去掉，也就是/vmlinuzMMMMMM 或 /initrdNNNN
也 可以不用root (hd[0-n]来指定/boot所在分区，要在kernel 和initrd 中指定；比如Linux的/根所位于的分区和/boot所位于的分区都是(hd0,6)，并且我们cat出来的/etc/fstab是Linux的/根分 区的文件系统的标签为LABEL=/，引导操作系统的例子如下；
grub>kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
grub>initrd (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img
grub>boot
或
grub>kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
grub>initrd (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img
grub>boot
如果/boot位于 /dev/hda6，也就是(hd0,5)，Linux的根/位于分区/dev/hda7，并且我们cat 出来的/etc/fstab 中/分区的标签为 LABEL=/。下面的两种方法都可以引导；
grub>kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
grub>initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img
grub>boot
或
grub>kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
grub>initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img
grub>boot
六、通过GRUB引导Windows操作系统；
1、通过编辑 menu.lst 来引导Windows 系统；
如果您的Windows所处于的分区在(hd0,0)，可以在menu.lst 加如下的一段就能引导起来了；
title WinXp
rootnoverify (hd0,0)
chainloader +1
如果您的机器有两块硬盘，而Windows 位于第二个硬盘的第一个分区，也就是(hd1,0)
您可以用grub的map来指令来操作把两块硬盘的序列对调，这样就不用在BIOS中设置了；在menu.lst中加如下的内容，比如下面的；
title WinXp
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd0,0)
chainloader +1
makeactive
如果Windows的分区不位于硬盘的第一个分区怎么办呢？比如在(hd0,2)；
这个也好办吧，把rootnoverify 这行的(hd0,0)改为 (hd0,2)
title WinXp
rootnoverify (hd0,2)
chainloader +1
makeactive
如果Windows的在第二个硬盘的某个分区，比如说是位于(hd1,2)，则要用到map指令；
title WinXp
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd1,2)
chainloader +1
makeactive
如 果有多个Windows 系统，怎么才能引导出来呢？应该用hide 和unhide指令操作；比如我们安装了两个Windows ，一个是位于(hd0,0)的windows 98 ，另一个是安装的是位于(hd0,1)的WindowsXP；这时我们就要用到hide指令了；
title Win98
unhide (hd0,0)
hide (hd0,1)
rootnoverify (hd0,0)
chainloader +1
makeactive
title WinXP
unhide (hd0,1)
hide (hd0,0)
rootnoverify (hd0,1)
chainloader +1
makeactive
2、通过GRUB指令来引导Windows ；
其实我们会写menu.lst了，在menu.lst中的除了title外，都是一条条指令；如果我们启动Windows ，只是输入指令就行了；
比如 Windows的分区在 (hd0,0)，我们在开机后，按ctrl+c ，进入GRUB的命令模式；就可以用下面的
grub> rootnoverify (hd0,0)
grub> chainloader +1
grub> boot
其它同理... ...
七、GRUB丢失或损坏的应对策略；
如果GRUB是Linux版本才出会这样的问题；WINGRUB可以不写在MBR上；所以不会出现这样的问题。WINGRUB用起来比较简单。menu.lst 和命令行的用法和Linux版本的GRUB是一样的；
1、由于重新安装Windows或其它未知原因而导致GRUB的丢失；
您可以通过系统安装盘、livecd进入修复模式；
请参考：《Linux 系统的单用户模式、修复模式、跨控制台登录在系统修复中的运用》
首先：您根据前面所说grub-install来安装GRUB到/boot所在的分区；要仔细看文档，/boot是不是处于一个独立的分区是重要的，执行的命令也不同；
其次：要执行grub ，然后通过 root (hd[0-n],y)来指定/boot所位于的分区，然后接着执行 setup (hd0)，这样就写入MBR了，比如下面的例子；
grub>root (hd0,6)
grub>setup (hd0)
grub>quit
重新引导就会再次出现MBR的菜单了或命令行的提示符了；
2、如果出现GRUB提示符，而不出现GRUB的菜单，如何引导系统；
存在的问题可能是/boot/grub/menu.lst丢失，要自己写一个才行；您可以用命令行来启动系统，进入系统后写一写menu.lst就OK了。前面已经谈过了；
写好后还要建一个grub.conf的链接，如下：
[root@localhost ~]# cd /boot/grub
[root@localhost grub]# ln -s menu.lst grub.conf
八、关于GRUB的未尽事宜；
GRUB有很多内容，比如对BSD的引导，还有一些其它指令的用法，我并没有在本文提到；主要我目前还未用到，如果您需要了解更多，请查看 《GNU GRUB 手册和FAQ》